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NBME 21 Answers

Block 1/Question#1
A 24-year-old woman with sickle cell disease comes to the ...
Serum parvovirus B19 IgM antibody test

Block 1/Question#2
A 6-month-old girl is brought to the physician because her ...
GM2

Block 1/Question#3
An investigator is studying the efficacy of distinct vaccine ...
Flagellin

Block 1/Question#4
A 67-year-old man comes to the emergency department because ...
Translation

Block 1/Question#5
A 45-year-old woman is brought to the emergency department 45 ...
Absorption atelectasis

Block 1/Question#6
A normal-appearing 17-year-old girl has never had a menstrual ...
Androgen insensitivity syndrome

Block 1/Question#7
A 30-year-old primigravid woman at 22 weeks' gestation comes ...
Listeria monocytogenes

Block 1/Question#8
A 52-year-old woman is admitted to the hospital because of ...
Speak with the two gynecologists to attempt to coordinate care

Block 1/Question#9
A 53-year-old woman who underwent an operation for breast ...
Breast: antagonist; Uterus: partial agonist

Block 1/Question#10
A 34-year-old woman is brought to the emergency department 30 ...
Primary metabolic acidosis with increased anion gap

Block 1/Question#11
A 27-year-old primigravid woman at 34 weeks' gestation is ...
Schistocytes

Block 1/Question#12
A 25-year-old nulligravid woman comes to the physician ...
Endometrial hyperplasia

Block 1/Question#13
A 25-year-old man develops shortness of breath after moving ...
Decreased alveolar Po2

Block 1/Question#14
A 21-year-old man is brought to the emergency department 45 ...
Streptococcus pneumoniae

Block 1/Question#15
A 35-year-old man comes to the physician because of a 1-day ...
Increased vascular permeability

Block 1/Question#16
A 43-year-old man comes to the physician for a follow-up ...
Aortic

Block 1/Question#17
A 7-year-old girl is brought to a clinic in a developing ...
Methionine

Block 1/Question#18
A 61-year-old woman is brought to the physician by her ...
Donepezil

Block 1/Question#19
A 22-year-old man has had frequent episodes of cutaneous ...
C1 esterase inhibitor (binds activated C1r, C1s)

Block 1/Question#20
A 10-year-old girl develops fever, malaise, and loss of ...
Retrograde transport through nerves

Block 1/Question#21
A 40-year-old man with type 2 diabetes mellitus comes to the ...
Stimulation of the peroxisome proliferator-activated receptor Îł

Block 1/Question#22
A 36-year-old man with AIDS elects to participate in a ...
Chemokine

Block 1/Question#23
A 59-year-old man comes to the physician because of a 3-month ...
Foci of keratinization

Block 1/Question#24
A 23-year-old man drinks alcohol heavily on a weekend. Which ...
Fatty change

Block 1/Question#25
A 28-year-old man is brought to the emergency department 30 ...
Dissecting aneurysm

Block 1/Question#26
A 62-year-old man who is a farmer comes to the physician ...
Actinic keratosis

Block 1/Question#27
A 60-year-old man is brought to the emergency department ...
Urethral disruption

Block 1/Question#28
A 47-year-old man is brought to the emergency department by ...
Mixed venous oxygen tension

Block 1/Question#29
A 34-year-old man comes to the physician because of a 2-week ...
Cluster headache

Block 1/Question#30
A newborn has female external genitalia and a 46,XY ...
Dihydrotestosterone

Block 1/Question#31
A 30-year-old woman comes to the office for a follow-up ...
Linoleic acid

Block 1/Question#32
A 50-year-old man has had progressive dyspnea on exertion ...
Usual interstitial pneumonitis

Block 1/Question#33
A 30-year-old man comes to the physician because of a ...
Varicella-zoster virus infection

Block 1/Question#34
A 30-year-old man develops urinary incontinence 2 weeks after ...
Pelvic nerves

Block 1/Question#35
A 7-year-old boy is brought to the physician by his mother ...
Increased blood lead

Block 1/Question#36
A 51-year-old woman comes to the physician because of a ...
Area labeled 'B' (Parietal cell)

Block 1/Question#37
A 35-year-old man with diabetic ketoacidosis has a decrease ...
Serum potassium concentration

Block 1/Question#38
A 47-year-old woman with aplastic anemia is being treated for ...
Amphotericin B

Block 1/Question#39
A 33-year-old woman comes to the physician because of fever, ...
Genital herpes

Block 1/Question#40
A physician prescribes a recently marketed drug for 20 ...
Phase 4

Block 1/Question#41
A 35-year-old woman comes to the physician because of a 2-day ...
Uroporphyrinogen decarboxylase

Block 1/Question#42
A 36-year-old woman undergoes a total hysterectomy and ...
Hyperplasia

Block 1/Question#43
A 52-year-old man is brought to the emergency department 30 ...
Histamine

Block 1/Question#44
A test has been developed to screen for human papillomavirus ...
Predictive value of a positive test

Block 1/Question#45
An 18-year-old man comes to the physician because of a 2-week ...
Pyruvate kinase

Block 1/Question#46
A 66-year-old man is brought to the emergency department ...
Lipopolysaccharide stimulation of toll-like receptor

Block 1/Question#47
A 26-year-old woman (III-2) comes to the physician for ...
50% in females but near 0 in males

Block 1/Question#48
A 44-year-old man is admitted to the hospital because of ...
Increasing cGMP

Block 1/Question#49
An 80-year-old woman comes to the emergency department ...
Hydrochlorothiazide

Block 1/Question#50
A photograph is shown of a myelin-stained cross section of a ...
Loss of sensation to vibration over both feet

Block 2/Question#1
A 27-year-old man comes to the physician for an examination ...
Schizoid

Block 2/Question#2
A 4-year-old girl is conscious but unable to breathe ...
Pseudocholinesterase deficiency

Block 2/Question#3
A 17-year-old boy returns to the locker room after football ...
Apocrine

Block 2/Question#4
An 18-year-old woman comes to the office because of a 2-week ...
Extensor carpi radialis brevis

Block 2/Question#5
A 2-week-old male newborn has a patent ductus arteriosus. ...
Higher than normal left ventricular cardiac output

Block 2/Question#6
A 38-year-old woman comes to the physician because of a ...
Serum calcium concentration

Block 2/Question#7
A 50-year-old man with rheumatoid arthritis comes to the ...
Anemia of chronic disease

Block 2/Question#8
A 55-year-old man is diagnosed with renal artery stenosis. ...
Cortex

Block 2/Question#9
A 40-year-old man is brought to the emergency department 45 ...
Metabolic acidosis and respiratory acidosis

Block 2/Question#10
A 42-year-old woman comes to the physician because of a ...
Rosacea

Block 2/Question#11
A 22-year-old woman, gravida 1, para 1, is brought to the ...
Internal iliac

Block 2/Question#12
A 66-year-old woman comes to the physician because of fever, ...
Diverticulitis

Block 2/Question#13
A 53-year-old woman with gastroesophageal reflux disease ...
Omeprazole

Block 2/Question#14
A 30-year-old woman comes to the office because she is ...
Abnormal brain development

Block 2/Question#15
A 48-year-old man is brought to the emergency department ...
Splenic and left renal

Block 2/Question#16
A 34-year-old woman comes to the physician because of a ...
Atrioventricular bundle

Block 2/Question#17
Scientists have identified the flawed gene that causes about ...
Mismatch repair

Block 2/Question#18
A 34-year-old woman comes to the physician because she has ...
“I’m concerned about how bad you’ve been feeling lately. Have you had any thoughts about death or wanting to be dead?”

Block 2/Question#19
A 3-year-old boy who recently immigrated to the USA is ...
Increased proportions of osteoid

Block 2/Question#20
A 14-year-old girl is brought to the physician by her mother ...
Trichotillomania

Block 2/Question#21
A 35-year-old woman undergoes flexible nasopharyngoscopy ...
Superior to the superior concha

Block 2/Question#22
A 33-year-old woman, gravida 4, para 4, is admitted to the ...
Transfusion-related acute lung injury

Block 2/Question#23
A 4-year-old boy with chronic granulomatous disease is ...
Macrophages producing interleukin-1 (IL-1)

Block 2/Question#24
A 65-year-old man dies in a motor vehicle collision. A ...
Squamous cell carcinoma

Block 2/Question#25
A 54-year-old man comes to the physician for a routine health ...
Area labeled 'F' (Efferent arteriole)

Block 2/Question#26
A healthy 32-year-old woman at 35 weeks' gestation is ...
Birth canal reflex

Block 2/Question#27
A 47-year-old woman with psoriasis comes to the physician for ...
“Most people find it difficult to stick to a routine. How did you do?”

Block 2/Question#28
A 64-year-old woman with type 2 diabetes mellitus and ...
Gemfibrozil

Block 2/Question#29
A healthy 25-year-old man is participating in a study of ...
Alanine

Block 2/Question#30
A 44-year-old man comes to the physician because of ...
Leukotriene C4: increased;
Arachidonic acid: increased;
Prostaglandin H2: decreased;
Prostaglandin E2: decreased


Block 2/Question#31
A 37-year-old man is brought to the emergency department 45 ...
Intercostal

Block 2/Question#32
A 17-year-old boy has the acute onset of lethargy, sore ...
Lymphocytes

Block 2/Question#33
A 68-year-old man comes to the physician because of a 1-month ...
Libido: normal; Nocturnal erections: normal

Block 2/Question#34
A 28-year-old man is brought to the emergency department ...
Inferior rectus and inferior oblique

Block 2/Question#35
A 4-month-old female infant is brought to the emergency ...
Hyponatremia

Block 2/Question#36
An investigator is conducting a study of antiretroviral ...
Enfuvirtide

Block 2/Question#37
A 17-year-old boy is evaluated for constitutional delay in ...
Craniopharyngioma

Block 2/Question#38
A 63-year-old man with bladder cancer starts treatment with ...
Tubulin polymerization stabilization

Block 2/Question#39
A 64-year-old man with bronchospastic pulmonary disease ...
Enhanced action of the agonist at β-adrenergic receptors

Block 2/Question#40
Acetaminophen and nonsteroidal antiinflammatory agents reduce ...
Prostaglandin E2

Block 2/Question#41
A 75-year-old woman has the sudden onset of Horner syndrome ...
Posterior inferior cerebellar

Block 2/Question#42
A 26-year-old man with HIV infection comes to the physician ...
Penicillin

Block 2/Question#43
A 78-year-old woman is brought to the emergency department by ...
Embolectomy

Block 2/Question#44
A 75-year-old man has the sudden onset of partial loss of ...
Parietal lobe, left

Block 2/Question#45
A 3-year-old boy is brought to the emergency department ...
Synthesis of factor X (Stuart factor)

Block 2/Question#46
An 8-year-old girl is brought to the physician for a ...
“Your daughter’s development is normal.”

Block 2/Question#47
A 55-year-old woman comes to the physician because of a ...
Increased parathyroid hormone

Block 2/Question#48
A 75-year-old man has fever, back pain, and pain on ...
Enterococcus faecalis

Block 2/Question#49
A 6-year-old girl is brought to the physician by her mother ...
Poxvirus

Block 2/Question#50
A 65-year-old woman comes to the emergency department because ...
Lung and common carotid artery

Block 3/Question#1
A 30-year-old woman develops dimness of vision
Ethambutol

Block 3/Question#2
A 40-year-old man with interstitial pulmonary fibrosis has a ...
Increased radial traction on airways

Block 3/Question#3
A 55-year-old African American man with hypertension is asked ...
Tell the patient that he can change his mind about participating

Block 3/Question#4
A clinical trial is conducted to compare the efficacy of a ...
Surgical procedure group: 400; Medical management group: 400

Block 3/Question#5
A 70-year-old woman is found to have persistent fever despite ...
Candida albicans

Block 3/Question#6
A 40-year-old African American woman comes to the physician ...
1,25-Dihydroxycholecalciferol

Block 3/Question#7
A 65-year-old man comes to the physician because of a 1-month ...
DNA fragmentation

Block 3/Question#8
A 55-year-old woman is brought to the emergency department by ...
Mammillary bodies

Block 3/Question#9
A 75-year-old woman is brought to the emergency department ...
Shrunken eosinophilic (red) neurons

Block 3/Question#10
A 30-year-old man has had intermittent severe lower abdominal ...
Cysteine

Block 3/Question#11
A 50-year-old man is found dead in bed at home. His family ...
Arrhythmia

Block 3/Question#12
A 55-year-old man with hypertension comes to the physician ...
Left renal artery atherosclerosis

Block 3/Question#13
A 40-year-old woman comes to the physician for an initial ...
Antagonizes VLDL-cholesterol secretion

Block 3/Question#14
A 35-year-old man is brought to the emergency department ...
Activation of adenylyl cyclase

Block 3/Question#15
A 47-year-old man has jaundice. Laboratory findings include ...
Obstruction of the bile duct

Block 3/Question#16
A 16-year-old boy is brought to the physician because of a ...
Exercise-induced asthma

Block 3/Question#17
A 66-year-old woman with pancreatic cancer comes to the ...
Short gastric

Block 3/Question#18
An 83-year-old man comes to the physician because of a 3-day ...
Bullous pemphigoid antigen

Block 3/Question#19
A 25-year-old woman develops increasing shortness of breath ...
Four-chamber dilation

Block 3/Question#20
A 68-year-old woman has had a fever and shortness of breath ...
Reactive granulocytosis

Block 3/Question#21
A screening program is instituted for detection of vaginal ...
10%

Block 3/Question#22
A 9-year-old boy has mild mental retardation and a 4-year ...
Rhabdomyoma

Block 3/Question#23
A 43-year-old woman dies after a 10-year illness ...
Area labeled ‘C’ (Caudate nucleus)

Block 3/Question#24
Diastolic blood pressures are obtained in two groups of 100 ...
Median of group Y: higher; Mode of group Y: higher

Block 3/Question#25
A 32-year-old woman comes to the physician because her sister ...
Dysplastic nevi

Block 3/Question#26
A 19-year-old woman comes to the office because of a 1-month ...
Descending colon

Block 3/Question#27
A 55-year-old woman with a benign nodule in the left lobe of ...
External carotid

Block 3/Question#28
A 1-year-old girl is admitted to the hospital because of a ...
Disruption of the secondary structure of collagen molecules

Block 3/Question#29
A 34-year-old man is evaluated after becoming light-headed ...
Number of impulses from carotid baroreceptor: decreased;
Sympathetic efferent activity: increased;
Parasympathetic efferent activity: decreased


Block 3/Question#30
A 41-year-old man comes to the physician because of a 6-week ...
Abduction of the upper extremity

Block 3/Question#31
A 28-year-old woman at 18 weeks' gestation has palpitations. ...
Free T4

Block 3/Question#32
A 72-year-old man comes to the physician because of a 2-week ...
Bleomycin

Block 3/Question#33
Left radial arterial and venous blood samples are drawn from ...
HCO3− transported in the plasma

Block 3/Question#34
A 39-year-old woman with rheumatoid arthritis develops ...
Membranous glomerulonephritis

Block 3/Question#35
A 63-year-old woman comes to the physician because of a 5-day ...
Increased resting cardiac output

Block 3/Question#36
Which of the following best explains why the use of an ...
Myeloma cells do not have membrane-bound surface immunoglobulin

Block 3/Question#37
A 5-year-old boy who has homocystinuria improves with ...
The line on the graph labeled ‘B’

Block 3/Question#38
A 28-year-old man develops a temperature of 39.9°C (103.8°F) ...
Granulocyte colony-stimulating factor

Block 3/Question#39
A 74-year-old woman with mild dementia is admitted to the ...
Inability to understand the severity and prognosis of her medical condition

Block 3/Question#40
A 65-year-old woman undergoes surgical repair of an aneurysm ...
Area labeled ‘A’ (Cranial nerve 3)

Block 3/Question#41
A 75-year-old woman comes to the physician's office because ...
Major depressive disorder

Block 3/Question#42
A 27-year-old primigravid woman at 39 weeks' gestation is ...
Shoulder dystocia

Block 3/Question#43
An undernourished 70-year-old man has fever, night sweats, ...
Interferon-Îł

Block 3/Question#44
A 23-year-old woman develops persistent sneezing each year in ...
Stabilization of mast cell membranes

Block 3/Question#45
A 28-year-old man comes to the physician for evaluation of ...
Fructose

Block 3/Question#46
A 38-year-old woman comes to the physician because of a ...
Patent foramen ovale

Block 3/Question#47
A 48-year-old man comes to the physician because of ...
Increased intestinal iron absorption

Block 3/Question#48
A 29-year-old woman comes to the physician because of a ...
Baclofen

Block 3/Question#49
The gene that codes for a protein normally found in the ...
Deletion of a hydrophobic amino acid sequence from the N terminus

Block 3/Question#50
A 32-year-old woman comes to the emergency department because ...
Arthropod vector

Block 4/Question#1
A 50-year-old woman has azotemia. Renal ultrasonography shows ...
Uterine cervix

Block 4/Question#2
A 23-year-old woman comes to the student health center ...
Obliterative endarteritis with lymphocytes and plasma cells

Block 4/Question#3
A study was performed that evaluated the relationship between ...
Odds ratio

Block 4/Question#4
The FOXO transcription factor responds to insulin signaling ...
Nuclear/cytoplasmic shuttling: yes;
Serine phosphorylation: yes
Ubiquitin-mediated proteolysis: no


Block 4/Question#5
An 11-year-old boy has had persistent pain in his right knee ...
Lung

Block 4/Question#6
A 55-year-old man comes to the physician because of a 2-month ...
Cortisol

Block 4/Question#7
A 14-year-old boy is brought to the physician by his mother ...
Inhaled glue

Block 4/Question#8
A 70-year-old woman has had recurrent pneumonia, fatigue, and ...
Euthyroid sick syndrome

Block 4/Question#9
A 60-year-old woman with psoriasis comes to the physician ...
Porphyria cutanea tarda

Block 4/Question#10
A 64-year-old man is evaluated for cough, dyspnea, and chest ...
Hyponatremia

Block 4/Question#11
A study is conducted on patients with asthma to compare a new ...
If the treatment really changes the mean asthma score by 0.4, there is an 80% chance that a study of this size will find a p-value < 0.05

Block 4/Question#12
A 24-year-old man with a history of drug abuse has nausea, ...
Heroin

Block 4/Question#13
A 4-month-old boy is diagnosed with a rare autosomal ...
Dilated rough endoplasmic reticulum

Block 4/Question#14
A 25-year-old woman has a 3-week history of bleeding gums ...
Autoantibodies against platelet glycoproteins

Block 4/Question#15
A 5-year-old boy is brought to the physician for a well-child ...
Lack of choroidal pigment deposition in the macula

Block 4/Question#16
A 40-year-old woman who had pneumonia due to Streptococcus ...
Surfactant

Block 4/Question#17
A 48-year old man is referred for evaluation of possible ...
Increase in width

Block 4/Question#18
A previously healthy 4-week-old male newborn is brought to ...
Pyloric stenosis

Block 4/Question#19
A 45-year-old woman comes to the emergency department because ...
Hepatopancreatic ampulla

Block 4/Question#20
A 7-month-old boy is brought to the physician 2 days after ...
46,XY

Block 4/Question#21
A 47-year-old man is treated with colchicine for acute gouty ...
Tubulin polymerization

Block 4/Question#22
A 57-year-old woman is brought to the emergency department ...
Ninth

Block 4/Question#23
An investigator is studying the regulation of pulmonary ...
Intravenous infusion of 0.9% saline for 5 minutes

Block 4/Question#24
A 56-year-old man undergoes a renal transplant. Five minutes ...
IgG plus complement

Block 4/Question#25
An 80-year-old woman cannot concentrate her urine above 450 ...
2.0

Block 4/Question#26
The immunosuppressive agent cyclosporin A (CsA) is a potent ...
Interleukin-2 (IL-2) gene transcription

Block 4/Question#27
A 65-year-old woman is being treated in the hospital for ...
“The two of you seem to have a very important relationship. Of course you may stay together.”

Block 4/Question#28
A 56-year-old man undergoes surgical resection of the ...
Release of cholecystokinin

Block 4/Question#29
A 22-year-old man comes to the physician because of a 2-month ...
Formation of destructive free radicals

Block 4/Question#30
A 5-year-old boy is admitted to the hospital because of ...
ApoC-II

Block 4/Question#31
A 48-year-old woman comes to the physician because of a ...
Paracrine stimulation of osteoclasts by osteoblasts

Block 4/Question#32
A 19-year-old college student says he hears voices." He was ...
Risperidone

Block 4/Question#33
A female newborn delivered at 26 weeks' gestation is found to ...
Retina

Block 4/Question#34
A healthy 8-year-old boy is brought to the physician by his ...
Stimulation of the release of biogenic amine neurotransmitters

Block 4/Question#35
A 50-year-old woman is admitted to the hospital because of a ...
Didanosine (ddI)

Block 4/Question#36
A 45-year-old man comes to the physician because of ...
Chondrosarcoma

Block 4/Question#37
A 66-year-old right-handed woman develops the acute onset of ...
Area labeled 'B' (Internal capsule)

Block 4/Question#38
A 62-year-old woman is brought to the physician by her ...
Instruct the patient to keep notes and lists to help her memory

Block 4/Question#39
A 46-year-old man comes to the physician because of a 2-month ...
1/15

Block 4/Question#40
A study is conducted to assess the normal mean serum urea ...
500 Men from a list of patients scheduled to be examined by a urologist

Block 4/Question#41
A 66-year-old man with stage IV colon cancer comes to the ...
Loperamide

Block 4/Question#42
A 20-year-old primigravid woman at 12 weeks' gestation comes ...
Multifactorial

Block 4/Question#43
A 4-year-old boy falls and lacerates his lower leg to the ...
Formation of fibrin clot

Block 4/Question#44
A 28-year-old woman with chronic renal failure (creatinine ...
Furosemide

Block 4/Question#45
During an experiment, an investigator observes that glutamate ...
NMDA receptors are blocked by Mg2+ at the resting membrane potential

Block 4/Question#46
A 14-year-old girl is brought to the physician for a ...
TP53

Block 4/Question#47
While lifting weights, a 24-year-old man develops a painful ...
Strangulation

Block 4/Question#48
A 75-year-old man with dementia, Alzheimer type, is brought ...
Encourage the family to come to a consensus based on their perception of the patient's wishes

Block 4/Question#49
A 76-year-old man comes to the physician because of a 2-week ...
Left thalamus

Block 4/Question#50
A 19-year-old woman is brought to the emergency department 30 ...
Scaphoid

Recent comments ...

... assoplasty made a comment on nbme21/block3/q#31 (A 28-year-old woman at 18 weeks' gestation has...)
 +49  upvote downvote
submitted by assoplasty(75)

I think the concept they’re testing is the increased TBG levels in pregnancy, and not just hyperthyroidism in general.

When screening for hypo/hyperthyroidism, TSH levels are ALWAYS preferentially checked because they are more sensitive to minute differences in T3/T4. Often times TSH levels can demonstrate a change even when T3/T4 levels are in the subclinical range. The only exception to this would be in pregnancy (and I guess maybe liver failure? I doubt they would ask this though). High estrogen levels prevents the liver from breaking down TBG, leading to increased TBG levels in the serum. This binds to free T4, decreasing the amount of available free T4. As a compensatory mechanism, TSH levels are transiently increased and the RATE of T4 production is increased to replenish baseline free T4 levels. However the TOTAL amount of T4 is increased.

The question is asking how to confirm hyperthyroidism in a pregnant woman --> you need to check FREE T4 levels (because they should be normal due to compensatory response). You cannot check TSH (usually elevated in pregnancy to compensate for increased TBG), and you cannot check total T4 levels (will be increased). You got the answer right either way but I think this is a different reasoning worth considering, because they can ask this concept in other contexts of hyper-estrogenism, and if they listed “TSH” as an answer choice that would be incorrect.

hungrybox  Extremely thorough answer holy shit thank u so much I hope you ACE Step 1
arkmoses  great answer assoplasty, I remember goljan talking about this in his endo lecture (dudes a flippin legend holy shit) but it kinda flew over my head! thanks for the break down!
whoissaad  you mean total amount of T4 is "not changed"? 2nd para last sentence.
ratadecalle  @whoissaad, in a normal pregnancy total T4 is increased, but the free T4 will be normal and rest of T4 bound to TBG. If patient is hyperthyroid, total T4 would still be increased but the free T4 would now be increased as well.
maxillarythirdmolar  To take it a step further, Goljan mentions that there are a myriad of things circulating in the body, often in a 1:2 ratio of free:bound, so in states like this you could acutally see disruption of this ratio as the body maintains its level of free hormone but further increases its level of bound hormone. Goljan also mentions that you'd see the opposite effect in the presence of steroids and nephrotic syndromes. So you could see decreased total T4 but normal free T4 because the bound amounts go down.
... nosancuck made a comment on nbme21/block1/q#5 (A 45-year-old woman is brought to the emergency...)
 +47  upvote downvote
submitted by nosancuck(63)

Bruh let me tell you a lil secret

PEEP prevents Atelectasis AKA dat LUNG COLLAPSE

Dont be worryin about random words they puts in front of the HIGH YIELD ones

hungrybox  literally LOL'd lmao I love this
... lnsetick made a comment on nbme21/block2/q#3 (A 17-year-old boy returns to the locker room after...)
 +40  upvote downvote
submitted by lnsetick(68)
  • APocrine = your armpits smell like an APE
  • ceRUMen = there’s no ROOM in your ears since they’re full of wax
  • EC-CRYne = when you ECercise, your pores are CRYing
  • SEBaceous = SEBum is SEEPing out of your pores
hungrybox  as an ape i'm offended
dr.xx  stop being an ape. evolutionize!
dbg  as a creationist i'm offended
maxillarythirdmolar  Also, Tarsal/Meibomian glands are found along the rims of the eyelid and produce meibum
snripper  So why is it apocrine? The dude is EXERCISING when playing football.
qball  The question asks about "the characteristic odor" i.e. body odor coming from the APEocrine glands. The Eccrine glands secrete water and electrolytes.
... drdoom made a comment on nbme21/block3/q#49 (The gene that codes for a protein normally found in...)
 +40  upvote downvote
submitted by drdoom(465)

The synthesis of virtually all proteins (mRNA->peptide) occurs in the cytoplasm.[1] That’s where all ribosomes reside, after all. Ribosomes, which are mostly just rRNA (~2/3 rRNA + 1/3 protein*, by weight), are assembled in the nucleus but only do their stuff once they get to the cytoplasm.

For a protein to leave its original hometown of the cytosol and become a resident of the nucleus or, sayyyyyy, the endoplasmic reticulum, it needs to have a little string of amino acids which shout “I belong in the nucleus!” or “I belong in the endoplasmic reticulum!”

Proteins ultimately destined for the ER contain an unimaginatively named string of amino acids known as “signal sequence,” which, for the purposes of the Step 1, is always at the N-terminus. The signal sequence tells other cytosolic proteins, “Hey! Take me (and the rest of the peptide of which I am part) to the ER!”

In the absence of this signal, a protein will remain in its “default” home of the cytosol.

Here’s a nice schematic showing the flow of proteins from initial synthesis to final destinations:


Endnotes

  1. “The synthesis of virtually all proteins in the cell begins on ribosomes in the cytosol.” (Essential Cell Biology, Alberts et al., 2014, p. 492)

*If you really want your mind blown, consider that even the protein subunits that make up that 1/3 of a ribosome are themselves initially synthesized in the cytosol; later, they are transported back into the nucleus via the nuclear pore.

qball  Awesome explanation. Now explain it to me like I'm 5.
drdoom  All baby peptides are born in the cytosol. But some baby peptides have a birthmark at their N-terminus. The birthmark tells a special mailman that this baby needs to be delivered somewhere else. If you chop off the birthmark, or erase it somehow, the mailman never knows to take the baby to its true home. The end. Now go to sleep or Santa will never bring you your presents.
... seagull made a comment on nbme21/block1/q#2 (A 6-month-old girl is brought to the physician...)
 +35  upvote downvote
submitted by seagull(838)

! I hate these with a burning F***ing passion. Thumbs up if you agree

mcl  Amen brother
praderwilli  Every morning: "I think i'll go over glycogen storage diseases, lysosomal storage diseases, and dyslipidemias after questions this afternoon." Every afternoon: Nah
mcl  oh my god are you me
praderwilli  I recently found a program called Pixorize. It's pretty much Sketchy for biochem. Wish I discovered it sooner cuz it has helped for a lot of the painful things like this!
tentorium  [special]
tentorium  [special]
tentorium  [special]
drhello  hello
burak  Cherry red spot basically means niemann-pick or tay sachs. Two differences between is: 1- No HSM in Tay Sachs, HSM in niemann-pick. 2- Both of them has muscle weakness but there is hyperreflexia in Tay Sachs, but areflexia in niemann pick disease. In stem cell HSM is not described and hyperreflexia noted.
abhishek021196  What is HSM?
mysticsoul  HSM - HepatoSplenoMegaly. Cherry red spots think of Tay Sachs, deficient enzyme - HeXosaminidase A, accumulated substrate GM2 ganglioside. Niemann-Pick - Spingomyelinase, Spingomyelin <- which is not even a choice. FA18 Pg 88
... niboonsh made a comment on nbme21/block4/q#45 (During an experiment, an investigator observes that...)
 +33  upvote downvote
submitted by niboonsh(214)

https://www.youtube.com/watch?v=4-DuvwoH2zQ if ur lazy like me, this is a good refresher video

d_holles  Amazing video dude. Somehow never learned this in neuro lol.
aag  Awesome video! Is this why you can give Mg2+ to eclampsia patients, because if so, mind goddamn blown.
... hayayah made a comment on nbme21/block3/q#33 (Left radial arterial and venous blood samples are...)
 +31  upvote downvote
submitted by hayayah(884)

the majority of carbon dioxide molecules are carried as part of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the RBCs. Carbonic anhydrase (CA) within RBCs quickly converts the carbon dioxide into carbonic acid (H2CO3). Carbonic acid is an unstable intermediate molecule that immediately dissociates into bicarbonate ions (HCO3-) and hydrogen (H+) ions.

The newly synthesized bicarbonate ion is transported out of the RBC into the plasma in exchange for a chloride ion (Cl−); this is called the chloride shift. When the blood reaches the lungs, the bicarbonate ion is transported back into the RBC in exchange for the chloride ion. The H+ ion dissociates from the hemoglobin and binds to the bicarbonate ion. This produces the carbonic acid intermediate, which is converted back into carbon dioxide through the enzymatic action of CA. The carbon dioxide produced is expelled through the lungs during exhalation.

hungrybox  Amazing explanation. Thank you!!
namira  in case anyone wants to visualize things... https://o.quizlet.com/V6hf-2fgWeaWYu1u23fryQ.png
ergogenic22  CO2 is carried in the blood is bound to hemoglobin, known as carbaminohemoglobin (HbCO2) (5%), dissolved CO2 (5%), bicarb is 90%
pg32  Nice explanation, but can anyone clarify how we know from the question that we are measuring HCO3 rather than dissolved CO2?
qball  @pg32 This question is asking about what accounts for the LARGER amount of co2 and the HCO3 buffer is about 85% of this transport and dissolved C02 is about 5-7%. https://courses.lumenlearning.com/wm-biology2/chapter/transport-of-carbon-dioxide-in-the-blood/
teepot123  fa 19 pg 656
... mcl made a comment on nbme21/block1/q#16 (A 43-year-old man comes to the physician for a...)
hyperfukus  this link is great! they're still kind of close together :( its so hard to tell for me w/o reference of the others
hyperfukus  this link is great! they're still kind of close together :( its so hard to tell for me w/o reference of the others
mannywillsee  So the way to differentiate Aortic valve from the others is by checking the lateral view, AV will be more medial than both tricuspid and mitral; tricuspid will be more anterior and mitral will be posterior while Pulmonary is doing its own thing
... notadoctor made a comment on nbme21/block1/q#32 (A 50-year-old man has had progressive dyspnea on...)
 +28  upvote downvote
submitted by notadoctor(121)

Usual interstitial pneumonitis is the histological definition of Idiopathic pulmonary fibrosis. We know that this patient has pulmonary fibrosis because the question states that there is fibrous thickening of the alveolar septa. This question was just testing that we knew the other names for Pulmonary Fibrosis.

aneurysmclip  Nbme back at it again
pg32  Is it still considered idiopathic pulmonary fibrosis is it appears to have been caused by an atypical pneumonia?
zevvyt  Why not Sarcoidosis? Wouldn't Sarcodosis also be a chronic inflamation with fibrous thickening?
... jambo2222 made a comment on nbme21/block4/q#5 (An 11-year-old boy has had persistent pain in his...)
 +25  upvote downvote
submitted by jambo2222(25)

It’s an osteosarcoma. Sarcoma = hematogenous mets. It’s in the legs so think how a DVT goes to lung. Same idea.

tinydoc  Perfect way to remember it. Thank you!
chandlerbas  Iused the mnemonic PB (lead) KeTtLe....looking at the stem it said "osteolytic mass" meaning that it has to be either Breast, Kidney, thyroid or lungs. none of the rest are options leaving lungs. but jambo2222 very noiice that works too!
jajajaja  @chandlerbas I think you might be using the mneumonic backwards- PB-KTL is for primary cancers that met to bone. For example, a primary lung cancer can met to bone and cause an osteolytic lesion. But in this case the primary cancer is the osteosarcoma. Meaning that the mneumonic doesn't actually apply to this question
chandlerbas  ya you're right good stuff!! I dont know why that made sense during the question...anyways to add to the other comments...osteosarcomas are aggressive and 10% metastasize to the lungs via hematogenously at the time of diagnosis.
... acanthosisnegrocans made a comment on nbme21/block2/q#40 (Acetaminophen and nonsteroidal antiinflammatory...)
 +25  upvote downvote
submitted by acanthosisnegrocans(25)

In the great words of Dr Sattar:

"Prostaglandin E2 mediates feeeeeeeeeever"

NSAIDs --> block prostaglandin syn

thisisfine   This is all I heard in my head
temmy  Me it was so weird
peridot  I do want to add, that while PGE2 is the right answer, FA19 p.213 says that IL-1 and TNF are involved as well. However, because the question asks about what is going on in the hypothalamus, the answer is PGE2. If the question had been asking about what the macrophages were releasing to influence the hypothalamus, then the answer would have been IL-1 or TNF (FA didn't specify if it was TNF-a though...).
... hungrybox made a comment on nbme21/block3/q#15 (A 47-year-old man has jaundice. Laboratory findings...)
 +22  upvote downvote
submitted by hungrybox(578)

why hemolysis is wrong:

There should almost never be straight up bilirubin in the urine. In hemolysis, the excess bilirubin is excreted in the bile. After bacterial conversion and reuptake, some will be excreted in the urine as urobilin. However, in obstructive disorders, the conjugated bilirubin will never have the opportunity to undergo bacterial conversion to sterco/urobilin. In this way, the conjugated bilirubin has no other way to be excreted other than directly in the urine.

credits to /u/alacran763 on reddit

... hungrybox made a comment on nbme21/block1/q#49 (An 80-year-old woman comes to the emergency...)
 +22  upvote downvote
submitted by hungrybox(578)

Hydrochlorothiazide is a thiazide diuretic => thiazide diuretics are associated with hypokalemia.

What other diuretics are associated with hypokalemia? Loop diuretics.

Why?

Inhibition of Na+ reabsorption occurs in both loop diuretics (inhibit NKCC cotransporter) and thiazide diuretics (inhibit NaCl cortransporter). All of this increased Na+ increases Aldosterone activity.

Relevant to this problem, Aldosterone upregulates expression of the Na+/K+ ATP antiporter (reabsorb Na+ into body, expel K+ into lumen). This results in hypokalemia in the body.

Hang on, there's more high yield info!

Aldosterone does one other important thing - activation of a H+ channel that expels H+ into the lumen.

So, given that this patient has hypokalemia, you know there is upregulation of Aldosterone. Do you think her pH would be high, or low? Exactly, it would be high because inc. Aldosterone => inc. H+ expelled into the lumen => metabolic akalosis.

Now you understand why both loop diuretics and thiazide diuretics can cause what's called "hypokalemic metabolic alkalosis."

hungrybox  jesus this answer was probably too long i'm sorry
meningitis  I disagree. It's the complete thought process needed for many Thiazide/Loop question that can be thrown. Thanks.
amirmullick3  This is what NBME should be providing with each question's correct answer! Thanks hungrybox!
amirmullick3  @hungrybox did you mean "All of this DECREASED Na increases aldosterone activity."?
pg32  Anyone care to explain why she feels she has, "lost [her] pep"? Is that due to the hypokalemia? Or hypercalcemia caused by the thiazides?
cmun777  @madojo @pg32 I assumed between her hypokalemia (which can cause weakness/fatigue) and possible contraction alkalosis those were the most likely causes for the "lost her pep" comment. I think if they wanted to indicate hypercalcemia to differentiate if loop diuretics were also in the answer choices they would certainly give more context for hypercalcemia sx
... hungrybox made a comment on nbme21/block2/q#17 (Scientists have identified the flawed gene that...)
 +21  upvote downvote
submitted by hungrybox(578)

when diff single strand repair mechanisms are used:

  • repair newly synthesized strand: mismatch repair (Lynch syndrome)
  • repair pyrimidine dimers caused by dat UV exposure: nucleotide excision repair (Xeroderma pigmentosum)
  • repair spontaneous/toxic alteration: base excision repair
meningitis  Brca: recombinant repair
usmlecrashersssss  also BLM gene bloom syndrome
brotherimodu  P.40 FA2019 lists the different DNA repair mechanisms
teepot123  fa '19 pg 382/3
... assoplasty made a comment on nbme21/block2/q#29 (A healthy 25-year-old man is participating in a...)
 +21  upvote downvote
submitted by assoplasty(75)

Fats are ketogenic (except odd chain FA), so they produce ketones for energy production (Acetyl-CoA) rather than glucose. If the question asked what the primary source of energy production was, it would still be glycogen (and not ketones), because this is within 24 hours. However after 24 hours the answer could be ketone bodies. Regardless, the question specifically said the pt had a serum glucose of 100, indicating that we are looking for something that provides a substrate for gluconeogenesis.

During periods of starvation, substrates for gluconeogenesis come from two sources: (1) breakdown of existing muscle, or (2) via odd-chain FA through propionyl-CoA. (*Valine also feeds into propionyl CoA, but is not involved during starvation --> see below)

(1) The alanine-pyruvate cycle provides this (glutamine in muscle + pyruvate --> alanine --> goes to liver --> transamination to alpha-ketoglutorate --> pyruvate is separated from glutamine --> glutamine goes to urea cycle, pyruvate goes on to gluconeogenesis). Lactate can also be used (this could have been a right answer if it were listed).

(2) Odd chain FAs are also glucogenic, but stearic acid (provided in the answer choice) isn’t odd chain, so it is only ketogenic and can be ruled out.

Although valine (and other branched a.a.) feed into Propionyl-CoA, they are not used in starvation because starvation strictly relies on hepatic gluconeogenesis. These a.a. are not metabolized in the liver because the liver lacks branched-chain a.a. transferase enzyme. In First Aid, Biochem section, under Fasting/Starvation, in both the “fasting state” (which is within the time frame of this question), or the “starvation state,” both utilize hepatic gluconeogenesis. My assumption is that valine is used during regular metabolism, and not during periods of starvation.

hello  I want to re-emphasize something that @assoplasty has already stated :). The Q-stem states serum glucose = 100, and the Q asks why the patient is able to maintain normoglycemia. Therefore, you can immediately eliminate choices A and C because acetoacetate and beta-hydroxybutyrate are sources of energy during ketogenesis -- ketogenesis does not provide glucose energy sources.
chandlerbas  ^ this checks out: valine and isoleucine are broken down in the muscle into branched chain 2 oxo acid via branched chain aminotransferase (reversible) then the valine and isoleucine leave the muscle and swims to the liver to be acted on by branched chain 2 oxo acid DH (irreversible). So bascially the process from taking BCAA valine and isoleucine requires 2 enzymes. the first enzyme is in the muscle, and the second enzyme is in the liver (for simplification purposes --> both organs contain both enzymes but dont have the same affinity for their substrate). source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1147506/?page=4 so you're right to say that the liver
toxoplasmabartonella  Thank you for such a great explanation. Isn't it glutamate instead of glutamine that combines with pyruvate in muscle to yield alanine for Cahill cycle?
almondbreeze  @ toxoplasmabartonella think you are right
... flashvoyger made a comment on nbme21/block4/q#25 (An 80-year-old woman cannot concentrate her urine...)
 +20  upvote downvote
submitted by flashvoyger(20)

The question is asking you how much water must the woman take in to maintain the same osmolality. This woman takes in 450 mOsm of solute per day. This is a unit of measurement -- think of it like grams.

For her to keep the same osmolality she must excrete 450 mOsm per day. The only way for her to excrete the solute is via the kidneys. The only way for her kidneys to excrete 450 mOsm is if they excrete 1 liter of water also. This is the max concentration that her kidneys can produce. (Her kidneys are not “powerful enough” to make her urine any more concentrated than that.)

This woman is also losing another liter of water to feces, sweating and respiration. This is the “insensible water loss”. That means if she losing 1 liter of water to sweat, respiration and feces per day plus 1 liter of water to urine (because she needs to dissolve her solute in something!), for her blood to stay the same osmolality, she must replace the water she lost thus must, at minimum, drink 2 liters of water per day.

jean_young2019  great explanationThank you
... sympathetikey made a comment on nbme21/block3/q#4 (A clinical trial is conducted to compare the...)
 +19  upvote downvote
submitted by sympathetikey(752)

• Per Protocol - Only include patients in the results who followed the protocol

• As treated - Data wise, only treat the subjects as they were treated (ex - if experimental patient does what the control patients are supposed to do, move that experimental patient to the control group

• Intention to treat - Include all patients in the groups they were originally randomized to

... mcl made a comment on nbme21/block2/q#30 (A 44-year-old man comes to the physician because of...)
 +19  upvote downvote
submitted by mcl(449)

This is a pretty good figure showing the conversion of membrane phospholipids to arachidonic acid/leukotrienes etc.

Blockade of COX enzyme by ibuprofen results in decreased production of prostaglandins H2 and E2, while causing the precursors to "back up" (increased arachidonic acid). This, in turn, results in increased production of leukotrienes.

... usmleuser007 made a comment on nbme21/block4/q#43 (A 4-year-old boy falls and lacerates his lower leg...)
 +19  upvote downvote
submitted by usmleuser007(278)
  1. Hemostasis (blood clotting): Within the first few minutes of injury,
    1. platelets in the blood begin to stick to the injured site.
    2. This activates the platelets, causing a few things to happen.
    3. They change into an amorphous shape, more suitable for clotting, and they release chemical signals to promote clotting.
    4. This results in the activation of fibrin, which forms a mesh and acts as "glue" to bind platelets to each other.
    5. This makes a clot that serves to plug the break in the blood vessel, slowing/preventing further bleeding.[5][6]

  2. Inflammation: During this phase, damaged and dead cells are cleared out, along with bacteria and other pathogens or debris.
    1. This happens through the process of phagocytosis, where white blood cells "eat" debris by engulfing it. 
    2. Platelet-derived growth factors are released into the wound that cause the migration and division of cells during the proliferative phase.

  3. Proliferation (growth of new tissue): In this phase, angiogenesis, collagen deposition, granulation tissue formation, epithelialization, and wound contraction occur.
    1. In angiogenesis, vascular endothelial cells form new blood vessels.
    2. In fibroplasia and granulation tissue formation, fibroblasts grow and form a new, provisional extracellular matrix (ECM) by excreting collagen and fibronectin.
    3. Concurrently, re-epithelialization of the epidermis occurs, in which epithelial cells proliferate and 'crawl' atop the wound bed, providing cover for the new tissue.
    4. In wound contraction, myofibroblasts decrease the size of the wound by gripping the wound edges and contracting using a mechanism that resembles that in smooth muscle cells.
    5. When the cells' roles are close to complete, unneeded cells undergo apoptosis.
  4. Maturation (remodeling): During maturation and remodeling,

    1. collagen is realigned along tension lines, and cells that are no longer needed are removed by programmed cell death, or apoptosis.

  5. Approximate times of the different phases of wound healing,[10] with faded intervals marking substantial variation, depending mainly on wound size and healing conditions, but image does not include major impairments that cause chronic wounds.
... g.liller@yahoo.com made a comment on nbme21/block3/q#5 (A 70-year-old woman is found to have persistent...)
 +18  upvote downvote
submitted by g.liller@yahoo.com(24)

Candida is a part of the normal flora of skin, could cause contamination of a central venous catheter. The question states that the organism is purple, budding, did not respond to broad spectrum antibiotics (aka they didn't use fluconazole or amphotericin B). Lastly, they showed it plated on blood agar and there was no hemolysis which eliminates staph (the only other possible contender here.)

Cryptococcus usually involves meningitis in immunocompromised pts. E. coli is gram negative sporothrix is usually transmitted by a thorn on a rose or someone with a history of gardening

hungrybox  Also, the yeast form of Candida is gram (+)
dr_jan_itor  I got thrown off by the part where they said "ovoid" and thought they were implying a cigar shape. I chose sporothrix for the morphology in spite of knowing that it clincally made no sense.
lilmonkey  I chose S. aureus before reading the question (looks like b-hemolysis). Then I saw "budding organisms" and picked the correct one.
the_enigma28  I think, elliptical budding yeast forms kind of excluded cryptococcus since its almost round -_-
the_enigma28  I think, elliptical budding yeast forms kind of excluded cryptococcus since its almost round -_-
lowyield  cryptococcus also doesn't take up gram stain because the shell is too thiqq
... beeip made a comment on nbme21/block3/q#4 (A clinical trial is conducted to compare the...)
 +18  upvote downvote
submitted by beeip(104)

I might be the only person on earth who got this one wrong, but regardless:

"ITT analysis includes every subject who is randomized according to randomized treatment assignment. It ignores noncompliance, protocol deviations, withdrawal, and anything that happens after randomization."[1]

yo  You're not. I also goofed.
seagull  https://www.youtube.com/watch?v=Kps3VzbykFQ This video is a pretty decent explination worth your time on the subject.
hungrybox  I got it right but I was only like 50% sure. So I appreciate it.
teepot123  ^ same video above used when I analysed my form 20 q which I got incorrect at time, its very clear at explaining this, helping me get it correct on this form
... drdoom made a comment on nbme21/block3/q#21 (A screening program is instituted for detection of...)
 +18  upvote downvote
submitted by drdoom(465)

2,500 students ... but you find out during your initial screen that 500 already have the disease. So, strikeout those people. That leaves 2,000 students who don’t have the disease.

Over the course of 1 year, you discover 200 students developed the infection. Thus:

200 new cases / 2,000 people who didn’t have the disease when you started your study = 10 percent

Tricky, tricky NBME ...

sympathetikey  Ah, I see. Thank you!
niboonsh  Im mad at how simple this question actually is
sahusema  Incidence is measured from those AT RISK. People with the disease are not considered to be at risk. So 2500 - 500 = 2000 people at-risk. Of those 2000, within one year 200 develop the disease. So 200/2000 of the at-risk population develop the disease. 20/2000 = 10% = incidence
daddyusmle  fuck im retarded
... hayayah made a comment on nbme21/block4/q#23 (An investigator is studying the regulation of...)
 +18  upvote downvote
submitted by hayayah(884)

Lymph flow rate is usually low. It is influenced primarily by the rate of lymph formation. For example, if blood capillary pressure is increased by arterial vasodilation or venous constriction, the flow rate of lymph increases. Also, the flow rate is affected by compression of lymphatics by contraction of neighboring musculature and by negative intrathoracic pressure (breathing).

Interstitial pressure (so pressure in the ECF, which would increase if given IV saline) and lymph flow are positively related. A small increase in interstitial volume greatly increases its pressure, promoting lymph flow that acts to restore the interstitial volume to normal.

more on this topic: https://www.ncbi.nlm.nih.gov/books/NBK53448/

linwanrun1357  Do not understand the breathing choice C and D) breath in and out are different?
khanhluong  I don't know if it's correct or not but how I approached C & D was that they both cause vasoconstriction in the arterioles (because this is the lung where hypoxia causes vasoconstriction), which decreases hydrostatic pressure through the capillaries and eventually decreases lymph flow. Maybe I completely got this question right for wrong reason, but I felt that it works with all of the answers. For F) I was thinking that it would cause increased capillary oncotic pressure which causes more fluid to go into the capillary than into the lymph vessels... Here's a picture: http://www.lymphedemablog.com/wp-content/uploads/2011/09/Lymphatics.gif
... hungrybox made a comment on nbme21/block4/q#20 (A 7-month-old boy is brought to the physician 2 days...)
 +18  upvote downvote
submitted by hungrybox(578)

This video explains genital embryology extremely well.

If you felt totally lost like me, watch the video first at 2x, then check out the bottom figure on pg. 608 in FA 2019.

Relevant to this question:

  1. SRY proteins stimulate development of testes
  2. This pt has testes => he must have the SRY gene on the Y chromosome
  3. MIF degrades the Mullerian duct, which would otherwise become the internal female genitalia
  4. This pt has internal female genitalia => didn't make enough MIF

Quiz yourself (answers in a separate post):

  1. This patient's disorder can be traced back to which cells?
  2. This patient had normal genitalia. If this patient had smaller genitalia than normal, that would be a defect in what enzyme?
ergogenic22  I like to work backwards. 1) patient has normal testicles on histology, normal appearing penis this must mean a Y chromosome is present, as testis determining factor is on the y chromosome (see above post point #2). I.e. you can eliminate choice A and B. Theoretically, 47XY and 47XYY could also present with female genitalia due to lack of MIF, but normal 46XY is more common
... madojo made a comment on nbme21/block1/q#39 (A 33-year-old woman comes to the physician because...)
 +17  upvote downvote
submitted by madojo(93)

Know your STD's baby ;-) (going through every other choice on this question):

  • Bacterial vaginosis caused by gardnerella vaginallis. Se a thin, off white discharge and fishy smell (fish in the garden). There's no inflammation Lab findings: pH greater than 4.5 (just like trichomoniasis), and a positive whiff test with KOH. Stem will say something about malodorous discharge and show the infamous CLUE CELLS if we are lucky. Not the answer for this question obviously because we would not expect vesicles with this bacterial disease.

  • Candidiasis is going to be your thick cottage cheese discharge, with inflammation. normal pH see pseudohyphae. Treat with topical nystatin, or oral fluconazole unless you're pregnant than use Clotrimazole. Again not going to see any vesicles.

  • Chancroid per uworld is associated with Haemophilus ducreyi you will have a Deep purulent painful ulcer with suppurative lymphadenitis. Will be told that patient has painful inguinal nodes, there may be multiple deep ulcers with gray-yellow exudate. You do cry with H. duCRYi This wouldn't be true for what our patient has in this question because we aren't told of any inguinal adenopathy. a link to a chancroid VDA

  • Chlamydia trachomatis causes lymphogranuloma venereum which is small shallow ulcers, painless, but then the large painful coalesced inguinal lymph nodes aka BUBOES. Compared with gonnorhea the discharge is more thinner and watery. Again not the case here as its painful and no mention of any BUBOOESS. The discharge in gonorrhea is more thicker. Both lead to PID, treat for both because confection is common. With both patient may have some sort of pain or burning sensation upon urination. Sterile pyuria though for both.

  • Condyloma accuminatum is a manifestation of HPV 6 + 11 (genital warts). They look like big cauliflowers. This is in contrast to Condyloma lata that you see in syphillis which is just a flatter latte brown looking macule.

  • Genital Herpes (the answer to the question) will present with multiple painful superficial vesicles or ulcerations with constitutional symptoms (fever, malaise) Just fits better than all the other choices I ran through.

  • Syphillis is the painless chancre. UW describes it as a single, indurated well circumscribed ulcer, with a clean base. See corkscrew organisms on DF microscopy. Keep in mind other painless ulcers are lymphogranuloma venereum of clamydia (but the buboes are whats painful not the ulcer), and granuloma inguinale (donovanosis - klebsiella granulomatis) but whats hallmark about this one is that its painless without lymphadenopathy

In short, be safe.

drdoom  this write-up is AWESOME ... but it also made me vomit.
b1ackcoffee  This is awesome, writeup, not the stds.
... feronie made a comment on nbme21/block3/q#7 (A 65-year-old man comes to the physician because of...)
 +17  upvote downvote
submitted by feronie(17)

Orchiectomy = ↓ testosterone production = ↓ DHT => prostate cells undergo apoptosis. (This mechanism is similar to using 5α-reductase blockers to treat BPH.)

Apoptosis is characterized by DNA fragmentation (pyknosis, karyorrhexis, karyolysis).

hungrybox  DNA fragmentation histopath: https://i.imgur.com/nxYW8vL.png Note that degradation in apoptosis is progressive. From pyknosis -> karyorrhexis -> karyolysis. Aka condensation -> fragmentation -> complete dissolution.
... cellgamesgojan made a comment on nbme21/block3/q#35 (A 63-year-old woman comes to the physician because...)
 +17  upvote downvote
submitted by cellgamesgojan(35)

AV Fistulas re-rout blood from the arterial system to the venous system, by-passing the Arterioles = Increase PL ---> INCREASE VR. All in all = Increase CO.

According to UWorld, the arterioles are a major source of resistance ... so bypassing the arterioles results in a decrease in Total Peripheral Resistance ... causing an increase in the rate and volume of blood returning to the heart. I am pretty sure there is more to the physiology behind this, but I hope this explained a little.

big92  "Immediately following creation, arteriovenous fistula (AVF) is associated with an increase in cardiac output (CO), achieved predominantly through a reduction in systemic vascular resistance, increased myocardial contractility, and an increase in stroke volume (SV) and heart rate. Over the following week, circulating blood volume increases in conjunction with increases in atrial and brain natriuretic peptides. These alterations are associated with early increases in left ventricular (LV) filling pressure with the potential for resultant impact on atrial and ventricular chamber dimensions and function." (PMID: 25258554) There's also another study by Epstein from the 1950s looking at the effects of AVF's effect on CO in men (PMID: 13052718). Apparently, the increase in resting CO is a big problem because it can lead to high-output cardiac failure (LVH).
hungrybox  Jesus big92 you went in on the research lmao u must be MSTP
temmy  big92 you are right. that is why pagets disease pagets have high output cardiac failure because of the av shunts.
... cantaloupe5 made a comment on nbme21/block1/q#3 (An investigator is studying the efficacy of distinct...)
 +17  upvote downvote
submitted by cantaloupe5(60)

Capsular polysaccharide vaccines are often conjugated to proteins to improve immunogenicity. Flagellin is the only answer choice that's a protein.

mambaforstep  both MHC 1 and 2 are present antigens that are PROTEINS (FA 2019 pg 100). so in order to elicit a T cell response, you need a protein (CANT BE A POLYSACC). that is why vaccines for polysaccaride antigens are often conjugated to PROTEINs--> so that we can elicit a T-cell response (FA 2019 pg 127).


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