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NBME 24 Answers

Block 1/Question#1
A researcher hypothesizes that exposure to more than 50 μg/L ...
Case-control study

Block 1/Question#2
A 43-year-old woman with a 2-year history of labile ...
Unopposed α-adrenergic tone

Block 1/Question#3
A 52-year-old woman comes to the physician because of severe ...
Intercostal

Block 1/Question#4
A 28-year-old man with AIDS has fever, headache, and ...
Lungs

Block 1/Question#5
The 35-year-old woman indicated by the arrow has a family ...
X-linked recessive

Block 1/Question#6
A 57-year-old woman requires intubation in the intensive care ...
Acute lung injury

Block 1/Question#7
A 65-year-old woman comes to the physician because of blood ...
Cigarette smoking

Block 1/Question#8
A 24-year-old woman at 28 weeks' gestation is brought to the ...
Tremor

Block 1/Question#9
The graph shows expiratory pressure-volume curves that ...
Diffuse pulmonary fibrosis

Block 1/Question#10
A 75-year-old man is brought unconscious to the emergency ...
Atherosclerosis

Block 1/Question#11
A 55-year-old man with type 1 diabetes mellitus comes to the ...
Persistent activation of voltage-gated Na+ channels in the nociceptor

Block 1/Question#12
A 26-year-old man comes to the physician for a follow-up ...
Increased number of LDL receptors on hepatocytes

Block 1/Question#13
A 4-year-old boy is brought to the emergency department by ...
Proliferative glomerulonephritis

Block 1/Question#14
A thin 66-year-old man is brought to the emergency department ...
Urine osmolality > plasma osmolality

Block 1/Question#15
Results of a 5-year screening program for HIV infection in a ...
5%

Block 1/Question#16
A 32-year-old man is brought to the emergency department ...
Flexion at the distal interphalangeal joint

Block 1/Question#17
A 3-year-old boy is brought to the emergency department ...
Annular pancreas

Block 1/Question#18
A 34-year-old woman with a long history of rheumatoid ...
Tuberculous osteomyelitis

Block 1/Question#19
A 35-year-old man comes to the physician because of a 1-week ...
Cluster headache

Block 1/Question#20
Immediately after a spontaneous vaginal delivery, a full-term ...
Fusion of the sclerotomes

Block 1/Question#21
A 35-year-old woman comes to the physician because of a ...
Foramen cecum

Block 1/Question#22
A 50-year-old man undergoes surgical transection of the ...
Adductor brevis

Block 1/Question#23
A 50-year-old man comes to the physician because of diarrhea ...
Generalized malabsorption

Block 1/Question#24
A 6-year-old girl is brought to the office by her mother ...
Pediculus humanus capitis

Block 1/Question#25
A 7-year-old boy has metabolic acidosis and persistent ...
Area labeled ‘B’ (Proximal convoluted tubule)

Block 1/Question#26
An 80-year-old woman with poorly controlled type 2 diabetes ...
Hematocrit: decreased;
Serum parathyroid hormone: increased;
Serum calcitriol: decreased


Block 1/Question#27
A 10-year-old girl with a lifelong history of intermittent ...
Palpable right ventricular lift

Block 1/Question#28
A 32-year-old woman comes to the physician because of a 7-day ...
Eosinophils

Block 1/Question#29
An 80-year-old woman comes to the physician because of a ...
Determination of erythrocyte sedimentation rate

Block 1/Question#30
A 55-year-old man is brought to the emergency department ...
Pulmonary capillary wedge pressure: increased;
Cardiac output: decreased;
Systemic vascular resistance: increased


Block 1/Question#31
An experimental study is conducted to examine the function of ...
Post-translational modification

Block 1/Question#32
A 24-year-old man receives an injection of histamine in the ...
Increased lymph flow

Block 1/Question#33
A 3-month-old girl is brought to the emergency department by ...
Human papillomavirus

Block 1/Question#34
A 62-year-old man comes to the physician for a follow-up ...
Sotalol

Block 1/Question#35
A 1616-g (3-lb 9-oz) male newborn is delivered to a ...
Bronchopulmonary dysplasia

Block 1/Question#36
A 4-year-old girl is brought to the physician because of a ...
Villous atrophy

Block 1/Question#37
A 25-year-old woman at 16 weeks' gestation comes to the ...
Increased hepatic production of T4-binding globulin

Block 1/Question#38
A 37-year-old woman comes to the physician because of nausea ...
Borderline

Block 1/Question#39
A 40-year-old man with AIDS develops severe diarrhea that is ...
Somatostatin

Block 1/Question#40
A 26-year-old man and his 25-year-old wife come to the ...
One in four will have 25% β-globin function and may require occasional transfusions

Block 1/Question#41
A 32-year-old woman who is 20 weeks' pregnant has had ...
Misoprostol

Block 1/Question#42
A 68-year-old woman with acute myelogenous leukemia begins ...
Granulocyte-macrophage colony-stimulating factor

Block 1/Question#43
After completing 6 courses of chemotherapy for cancer of the ...
Doxorubicin

Block 1/Question#44
A 24-year-old man is brought to the office because of fever ...
Alteration in DNA gyrase

Block 1/Question#45
A 71-year-old man is brought to the emergency department ...
Area labeled ‘D’ (Posterior inferior cerebellar artery)

Block 1/Question#46
A 10-year-old girl is scheduled to undergo fixation of a ...
Succinylcholine

Block 1/Question#47
A 35-year-old man comes to the physician 1 week after he had ...
Increased serum angiotensin II concentration

Block 1/Question#48
A 70-year-old man is brought to the emergency department ...
Stroke volume: decreased;
Left ventricular end-diastolic volume: increased;
Cardiac output: decreased


Block 1/Question#49
A 58-year-old man is brought to the emergency department 1 ...
Ruptured spleen

Block 1/Question#50
An 11-year-old boy is brought to the emergency department by ...
Intracellular and extracellular dehydration

Block 2/Question#1
A 73-year-old woman has had easy fatigability for 2 years. ...
Failure of conversion of N5-methyltetrahydrofolate to tetrahydrofolate

Block 2/Question#2
A 45-year-old man comes to the physician because of ...
Oxygen saturation

Block 2/Question#3
A 13-year-old boy is brought to the physician by his mother ...
This will typically resolve within the next 12 to 18 months.

Block 2/Question#4
A 57-year-old man has had hoarseness and difficulty ...
Area labeled ‘F’

Block 2/Question#5
A 55-year-old man is diagnosed with coronary artery disease. ...
Decreased adherence

Block 2/Question#6
A 50-year-old woman is admitted to the hospital for ...
Factitious disorder

Block 2/Question#7
A 75-year-old man with a 10-year history of progressive renal ...
Hydrostatic pressure in Bowman space

Block 2/Question#8
A 17-year-old girl is brought to the hospital by ambulance 45 ...
Beneficence

Block 2/Question#9
In which of the following stages of the cell cycle are ...
G2

Block 2/Question#10
A 29-year-old man is brought to the emergency department ...
Lateral pterygoid

Block 2/Question#11
A public health consultant is contacted by a health ...
Regular exercise

Block 2/Question#12
An 80-year-old man is admitted to the hospital because of a ...
20

Block 2/Question#13
An 80-year-old woman, gravida 4, para 4, comes to the office ...
Damage to the rectovaginal septum

Block 2/Question#14
A 25-year-old man comes to the emergency department because ...
Heroin

Block 2/Question#15
An investigator is studying a new drug for the treatment of ...
Free radical formation

Block 2/Question#16
A 28-year-old man with chronic hepatitis C comes to the ...
HIV

Block 2/Question#17
A 68-year-old man comes to the physician because he is ...
Normal aging

Block 2/Question#18
A 68-year-old man has loss of pain and temperature sensations ...
Right dorsolateral medulla

Block 2/Question#19
A 70-year-old man comes to the physician because of a 1-year ...
Alveolar-arterial Po 2 difference

Block 2/Question#20
A 52-year-old man is admitted to the hospital for treatment ...
Granulation tissue

Block 2/Question#21
A 50-year-old woman with HIV infection comes to the physician ...
Zidovudine

Block 2/Question#22
A 3-month-old boy is brought to the physician because of ...
Peroxisomes

Block 2/Question#23
A 9-year-old boy who was adopted from an African country 2 ...
E

Block 2/Question#24
A 59-year-old man has repeated episodes of gouty arthritis ...
Probenecid

Block 2/Question#25
A 35-year-old African American man comes to the physician for ...
Palms

Block 2/Question#26
A 35-year-old man is brought to the emergency department ...
Catecholamine-mediated intracellular shifts of K+

Block 2/Question#27
A 47-year-old man comes to the physician because of recurrent ...
Monosodium urate

Block 2/Question#28
A 3-year-old boy with AIDS develops giant cell pneumonia 3 ...
Negative-stranded RNA

Block 2/Question#29
A 65-year-old woman with well-controlled type 2 diabetes ...
Atherosclerosis

Block 2/Question#30
A 35-year-old man with small cell carcinoma of the lung has ...
ACTH

Block 2/Question#31
A patient with cancer who is being treated with high-dose ...
Granulocyte colony-stimulating factor

Block 2/Question#32
A 35-year-old woman undergoes a left oophorectomy because of ...
Ureter

Block 2/Question#33
A 58-year-old man comes to the physician because of a 3-day ...
Escherichia coli

Block 2/Question#34
A 40-year-old man who goes horseback riding 3 to 4 times ...
Myositis ossificans

Block 2/Question#35
A 55-year-old woman comes to the physician because of a ...
Lower motoneurons

Block 2/Question#36
A 27-year-old woman comes to the physician for a follow-up ...
Transforming growth factor-β

Block 2/Question#37
In a culture of motile spore-forming bacteria, which of the ...
Irradiation with x-rays

Block 2/Question#38
A 65-year-old man comes to the physician because of ...
Paroxetine

Block 2/Question#39
A 3-year-old boy has short stature and extremities and a ...
Endochondral ossification

Block 2/Question#40
A 4-year-old boy has a 1-cm round midline mass just inferior ...
Tongue

Block 2/Question#41
A 56-year-old man who is admitted to the hospital for ...
Determine whether the patient has decision-making capacity

Block 2/Question#42
A 3-week-old female newborn is brought to the physician for a ...
The patient has another mutation that was not included in the previous analysis

Block 2/Question#43
A 35-year-old woman has difficulty urinating 2 days post ...
Parasympathomimetic stimulation

Block 2/Question#44
A 35-year-old man with quadriplegia develops a urinary tract ...
Area labeled ‘B’ (Proximal convoluted tubule)

Block 2/Question#45
A 2-year-old boy is brought to the physician because of ...
Peptide transporter (TAP)

Block 2/Question#46
In a study of drug action on neoplastic cells in culture, ...
Vincristine

Block 2/Question#47
A 73-year-old man has an incurable malignant neoplasm of the ...
Both legal and ethical

Block 2/Question#48
The breakdown of dipeptides and tripeptides to free amino ...
Intestinal mucosa

Block 2/Question#49
A 17-year-old girl comes to the physician because she has ...
Increased serum testosterone concentration

Block 2/Question#50
An obese 57-year-old man comes to the physician for a routine ...
Normal ciliated columnar epithelium replaced by normal squamous epithelium

Block 3/Question#1
A 3-year-old girl has a history of recurrent infections. In ...
NADPH oxidase

Block 3/Question#2
A 28-year-old man has a blood pressure cuff placed around his ...
Adenosine

Block 3/Question#3
A 37-year-old woman with HIV infection is brought to the ...
Nucleoside reverse transcriptase inhibitor

Block 3/Question#4
A 27-year-old man comes to the physician because he and his ...
Injections of gonadotropins

Block 3/Question#5
A 37-year-old man is admitted to the hospital because of ...
Autoimmune adrenalitis

Block 3/Question#6
A 43-year-old woman comes to the physician because of a ...
Alkaline phosphatase

Block 3/Question#7
A 21-year-old woman with asthma comes to the physician ...
Phase 3

Block 3/Question#8
A 37-year-old man who is a farmworker comes to the emergency ...
Synaptobrevin

Block 3/Question#9
A 43-year-old woman comes to the physician because of a ...
Metastatic carcinoma

Block 3/Question#10
Serum cholesterol concentrations are measured as part of a ...
16%

Block 3/Question#11
The pedigrees of patients with schizophrenia most closely ...
Diabetes mellitus, type 1

Block 3/Question#12
A 35-year-old woman with asthma comes to the emergency ...
Thiabendazole

Block 3/Question#13
An 83-year-old woman is brought to the physician by her ...
Discussion of the diagnosis with the patient privately

Block 3/Question#14
A cohort study is done to evaluate the association between ...
0.05 < p < 1.0

Block 3/Question#15
A 17-year-old girl has significant blood loss after being ...
δ-Aminolevulinate

Block 3/Question#16
An 18-year-old woman is brought to the physician because of ...
Respiratory acidosis

Block 3/Question#17
HOX genes play a role in embryogenesis through which of the ...
Regulation of transcription

Block 3/Question#18
A 55-year-old man with alcoholism is brought to the emergency ...
Competitive inhibitor

Block 3/Question#19
A 23-year-old primigravid woman at 22 weeks' gestation is ...
Ask the patient if she would allow the examination if her husband is present at all times

Block 3/Question#20
A 33-year-old woman comes to the physician because of a ...
Defect in a cell membrane anchor protein

Block 3/Question#21
A 7-year-old girl is brought to the emergency department (ED) ...
Factitious disorder imposed on another

Block 3/Question#22
A 32-year-old woman recently diagnosed with AIDS is at ...
Epstein-Barr virus-induced brain lymphoma

Block 3/Question#23
A 32-year-old woman comes to the physician because of pain ...
Buccinator

Block 3/Question#24
A 3-month-old boy is brought to the emergency department ...
Gluconeogenesis

Block 3/Question#25
An investigator is studying a new virus isolated from a ...
Coronavirus

Block 3/Question#26
A 54-year-old man with a myocardial infarction becomes ...
Decrease in intracellular ATP concentrations

Block 3/Question#27
A 27-year-old man who works from home as a software engineer ...
Avoidant

Block 3/Question#28
A 22-year-old man is brought to the emergency department 30 ...
Area labeled ‘E’ (Cerebellum, posterior lobe)

Block 3/Question#29
Drug X is given to a 25-year-old normal subject. This drug ...
Partial agonist at β-adrenergic receptors

Block 3/Question#30
A 38-year-old woman comes to the physician because of ...
Intraductal papilloma

Block 3/Question#31
A 65-year-old man is brought to the emergency department 30 ...
Systemic vascular resistance: increased;
Pulmonary vascular resistance: decreased;
Pulmonary capillary wedge pressure: increased


Block 3/Question#32
A 15-year-old girl is brought to the physician because of a ...
CD8+ T lymphocytes

Block 3/Question#33
A 12-year-old boy is brought to the physician by his mother ...
Nocturnal luteinizing hormone pulses

Block 3/Question#34
An otherwise healthy 35-year-old man sustains a fracture of ...
Decreased blood volume

Block 3/Question#35
A 4-year-old girl has a history of multiple bone fractures ...
Scar formation

Block 3/Question#36
A 1-month-old male newborn is brought to the physician for a ...
Tyrosine

Block 3/Question#37
A man accidentally touches the surface of a hot stove; 20 ...
Interendothelial gaps in venules

Block 3/Question#38
A 55-year-old man comes to the physician because of a 2-week ...
Serum free thyroxine (FT4): increased;
Serum free triiodothyronine (FT3): increased;
Thyroidal iodine uptake: decreased


Block 3/Question#39
A 34-year-old woman is brought to the emergency department 45 ...
Lunate

Block 3/Question#40
A 2-year-old boy is brought to the emergency department ...
Polysaccharide protein conjugate vaccine

Block 3/Question#41
A 30-year-old man develops tingling around the lips and mouth ...
Sodium

Block 3/Question#42
Which of the following terms best describes the fibrous ...
Lamins

Block 3/Question#43
A 35-year-old woman with a long-standing history of asthma ...
Infiltration of lymphocytes and monocytes

Block 3/Question#44
A 62-year-old man comes to the physician for a follow-up ...
Serum gastrin

Block 3/Question#45
A 59-year-old woman has a 10-year history of progressive ...
Neural crest cells

Block 3/Question#46
A 15-year-old girl with cystic fibrosis has a mutation in the ...
Endoplasmic reticulum

Block 3/Question#47
A 22-year-old woman comes to the physician for a follow-up ...
Intrauterine device

Block 3/Question#48
A 62-year-old man comes to the physician because of a 2-month ...
Phantom limb pain

Block 3/Question#49
A 20-year-old woman with asthma comes to the physician ...
Ask the roommate not to smoke in the apartment

Block 3/Question#50
A group of physicians submits a report to a medical journal ...
Case series

Block 4/Question#1
A 30-year-old woman comes to the physician for follow-up ...
Glycine and succinyl CoA

Block 4/Question#2
A full-term male newborn has lethargy, poor feeding, and ...
Enzymatic reaction labeled ‘C’

Block 4/Question#3
A 23-year-old woman is brought to the emergency department ...
Renal tubular acidosis

Block 4/Question#4
A 63-year-old woman develops flank pain, tachycardia, and ...
ABO incompatibility

Block 4/Question#5
A 45-year-old man comes to the physician because of a 3-day ...
Muscle biopsy

Block 4/Question#6
A 68-year-old woman comes to the physician because of a ...
Inferior mesenteric and superior mesenteric

Block 4/Question#7
A 3-year-old girl is brought to the physician for a ...
Spontaneous regression

Block 4/Question#8
A 1-week-old newborn is brought to the physician because of ...
Organic acid metabolism disorder

Block 4/Question#9
A 10-year-old boy who was adopted from the Democratic ...
Black fly

Block 4/Question#10
A 60-year-old woman is receiving cisplatin therapy for ...
Hyporeflexia

Block 4/Question#11
A 53-year-old woman comes to the physician because of a ...
Fixed cardiac output in spite of increased demand

Block 4/Question#12
A 25-year-old woman takes an overdose of barbiturates and is ...
Extubate the patient and discontinue mechanical ventilation; make no attempt to do cardiopulmonary resuscitation in case of cardiac or respiratory failure

Block 4/Question#13
A 90-year-old man has a 1-week history of constipation and ...
Incarcerated inguinal hernia

Block 4/Question#14
A new screening test for colon cancer is done in 86 patients ...
118/124 = 95%

Block 4/Question#15
A 15-month-old boy is brought to the physician by his mother ...
Migration

Block 4/Question#16
A 24-year-old woman who has diffuse toxic goiter (Graves ...
Phosphate: increased;
Parathyroid hormone: decreased;
25-hydroxyvitamin D: normal


Block 4/Question#17
A 63-year-old woman undergoes operative repair of a leaking ...
Decreased movement through the arachnoid villi

Block 4/Question#18
A 64-year-old man undergoes surgical repair of an abdominal ...
Artery of the ductus deferens

Block 4/Question#19
A 38-year-old woman, gravida 4, para 4, comes to the ...
Internal anal sphincter

Block 4/Question#20
Forty of 100 attendees at a company Christmas party develop ...
Vibrio parahaemolyticus

Block 4/Question#21
An otherwise healthy 45-year-old man comes to the office ...
Aphthous ulcers

Block 4/Question#22
A 45-year-old man is brought to the emergency department 2 ...
Renal calculi in the left ureter

Block 4/Question#23
At 2:00 am, after sleeping for 5 hours, a 32-year-old man ...
Phenylethanolamine N-methyltransferase

Block 4/Question#24
A 13-year-old girl who has a 6-year history of type 1 ...
Discuss further the impact of the patient's illness on the family

Block 4/Question#25
A 26-year-old man is brought to the emergency department 40 ...
Pericardial tamponade

Block 4/Question#26
A 10-year-old girl is brought to the physician by her mother ...
Ovarian Sertoli-Leydig cells

Block 4/Question#27
A 19-year-old man has had weakness of the muscles of his neck ...
Polyneuropathy

Block 4/Question#28
A clinical study is designed to evaluate the association of ...
10%

Block 4/Question#29
A 56-year-old man has a 3-year history of progressive memory ...
Presenilin

Block 4/Question#30
An investigator is studying an outbreak of Escherichia coli ...
Only cookies are independently associated with E. coli cases

Block 4/Question#31
In a study of antibiotic resistance, a strain of Escherichia ...
Conjugation

Block 4/Question#32
A 45-year-old man with hypercholesterolemia (LDL 260 mg/dL) ...
Increased synthesis of LDL receptors

Block 4/Question#33
A 12-year-old boy is brought to the physician by his mother ...
Inhalant abuse

Block 4/Question#34
A 55-year-old woman comes to the physician for a routine ...
Neuroendocrine cell

Block 4/Question#35
An investigator is conducting a study of a novel protein in ...
Basal keratinocyte:suprabasal keratinocyte

Block 4/Question#36
A 68-year-old woman comes to the emergency department 2 hours ...
Alendronate

Block 4/Question#37
A male newborn is delivered in the hospital at 40 weeks' ...
Ingestion of undercooked meat

Block 4/Question#38
A 33-year-old woman at 34 weeks' gestation has a grade 2/6 ...
Stroke volume

Block 4/Question#39
A 30-year-old woman comes to the physician because of a ...
Decreased afferent arteriolar resistance

Block 4/Question#40
A 25-year-old woman is brought to the emergency department by ...
Pulmonary capillary leakage

Block 4/Question#41
A 30-year-old man who is a migrant farm worker comes to the ...
Formation of hypnozoites

Block 4/Question#42
A 40-year-old man who recently immigrated to the USA from ...
Adenine

Block 4/Question#43
A 72-year-old woman with coronary artery disease comes to the ...
Neointima formation in the right coronary stent

Block 4/Question#44
A 71-year-old woman with non-Hodgkin lymphoma is diagnosed ...
Leucovorin

Block 4/Question#45
A 40-year-old woman with a 25-year history of type 1 diabetes ...
Secreted by the proximal tubule

Block 4/Question#46
A 22-year-old woman comes to the physician because of nausea ...
Pineal gland

Block 4/Question#47
A 40-year-old man comes to the physician because of a 6-month ...
HNPCC syndrome

Block 4/Question#48
A 55-year-old woman is brought to the physician by her ...
Posterior cerebral

Block 4/Question#49
A 27-year-old man sustains a spinal cord transection at C-8 ...
Penile stimulation

Block 4/Question#50
A 47-year-old man comes to the physician because of abdominal ...
Superior rectal vein

Recent comments ...

... seagull made a comment on nbme24/block2/q#48 (The breakdown of dipeptides and tripeptides to free...)
 +62  upvote downvote
submitted by seagull(413)

The semantics of this question made me vomit blood.

One day a patient will look me in the eyes and ask, "Where are tripetides broken down?" I will smile at them and say, "the intestinal mucosa and not the duodenum." They'll smile back and I'll walk away and think of this moment as I jump from the window.

sympathetikey  Too real.
mcl  how do i upvote multiple times
trichotillomaniac  I made an account solely so I could upvote this.
dragon3  ty for the chuckle
cinnapie  @trichotillomaniac Same
... drdoom made a comment on nbme24/block3/q#2 (A 28-year-old man has a blood pressure cuff placed...)
 +30  upvote downvote
submitted by drdoom(185)

After the cuff is tied, the cells and tissue distal to the cuff will continue consuming ATP (ATP->ADP), but no fresh blood will be delivered to “clear” what will be an accumulating amount of ADP and other metabolites. ADP (=Adenosine) is itself a proxy of consumption and drives vasodilation of arteries! (Evolution is smart!) Increasing ADP/Adenosine in a “local environment” is a signal to the body that a lot of consumption is occurring there; thus, arteries and arterioles naturally dilate to increase blood flow rates and “sweep away” metabolic byproducts.

lispectedwumbologist  You're a good man. Thank you.
drdoom  So glad it helped!
seagull  very well put, thank you
... xxabi made a comment on nbme24/block4/q#43 (A 72-year-old woman with coronary artery disease...)
 +23  upvote downvote
submitted by xxabi(90)

Stent thrombosis vs re-stenosis. Stent thrombosis is an acute occlusion of a coronary artery stent, which often results in acute coronary syndrome. Can be prevented by dual antiplatelet therapy or drug-eluting stents. Re-stenosis is the gradual narrowing of the stent lumen due to neointimal proliferation, resulting in anginal symptoms.

... lsmarshall made a comment on nbme24/block2/q#49 (A 17-year-old girl comes to the physician because...)
 +16  upvote downvote
submitted by lsmarshall(191)

Androgen Insensitivity Syndrome - Defect in androgen receptor resulting in normal-appearing female (46,XY DSD). Functioning testes causes increased testosterone at puberty, which is converted to estrogen peripherally, giving female secondary sexual characteristics (female external genitalia). Lack of androgen receptor function leads to absent or scant axillary and pubic hair. Patients have rudimentary vagina, but uterus and fallopian tubes absent.

Androgen insensitivity syndrome is the answer but you might have considered Müllerian agenesis (Mayer-Rokitansky- Küster-Hauser syndrome).

Mullerian agenesis will have normal hormone levels and may present as 1° amenorrhea (due to a lack of uterine development) in females with fully developed 2° sexual characteristics (functional ovaries). Hair development is normal as well. Patients also have normal height.

Seems like this question did not give us much to distinguish besides height and tanner stage 1 pubic/axillary hair.

dbg  100% agreed. Mullerian agenesis was on my mind too. The full breast development kept me fixed at this dx. Did not think how high testosterone at this age and insensitivity would push towards peripheral conversion to estrogen and hence breast development. Thanks.
... lsmarshall made a comment on nbme24/block4/q#8 (A 1-week-old newborn is brought to the physician...)
 +15  upvote downvote
submitted by lsmarshall(191)

Urea Cycle Disorders > Isolated severe hyperammonemia (> 1000; i.e., no other severe metabolic disturbances

Ornithine transcarbamylase deficiency > (most common urea cycle dis.) orotic acidemia/aciduria, hyperammonemia

Organic Acidemias > Hyperammonemia, anion-gap acidosis, ketosis (from hypoglycemia)

Medium-chain acyl-CoA dehydrogenase deficiency > Hyperammonemia, hypoketotic hypoglycemia (seen in β-oxidation disorders, EXCEPT adrenoleukodystrophy)

Liver dysfunction > Hyperammonemia, LFTs messed up, older pt.

lsmarshall  Summary of metabolic issues relating to hyperammonemia
seagull  i'm leaning towards Ornithine transcarbamylase deficiency.
notadoctor  Not sure why this isn't considered a mitochondrial disorder since the issue is Ornithine transcarbamylase deficiency in the mitochondria?
charcot_bouchard  if it was mitochondrial disorder no one would escape
wowo  figure in OTC deficiency, they might have to explicitly mention the orotic aciduria AND typically presents earlier, around 24-48hrs of life after they've fed (at least per BB) + also per BB, propionic acidemia and MM acidemia have an onset of weeks to months and lead to build up of organic acids --> acidemia in addition to hyperammonemia (not sure why, but several aa enter the TCA cycle via propionyl CoA --> methylmalonyl CoA --> succinyl CoA, but now this is defunct d/t enzyme deficiencies...?). Anywho, propionic acidemia described on FA2019 p85, but doesn't list hyperammonemia
artist90  i think it cannot be Ornithine transcarbamylase deficiency bc it is XR disease. this pt has a healthy 2yr old brother which rules out X-linked recessive disease correct me if i m wrong
artist90  it is 100% Propionic acidemia Uworld Q-id: 1340. it is an exact copy question of uworld. i got it wrong bc i forgot these are organic acids. But i am still confused on 2 things 1-how does acidosis cause Hypoglycemia and Ketosis. 2-why is Ammonia elevated in these pts bc urea cycle will be fine?
yb_26  1) hyperammonemia is seen in all urea cycle disorders except arginase deficiency 2) organic acids directly inhibit urea cycle => hyperammonemia (from UWorld)
yex  According to UW, there is another question # 1341. This one refers to methylmalonic acidemia (ORGANIC ACIDEMIA). HYPOGLYCEMIA results from overall increased metabolic rate leading to increased glucose utilization and direct toxic (-) of gluconeogenesis by organic acids. The presence of hypoglycemia leads to increased free fatty acid metabolism that produces KETONES, resulting in a further anion gap met acidocis. Finally, organic acids also directly (-) the urea cycle, leading to HYPERAMMONEMIA.
... seagull made a comment on nbme24/block2/q#49 (A 17-year-old girl comes to the physician because...)
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submitted by seagull(413)

at BMI 15 not only has she never had a period but she never had a meal.

sympathetikey  You're on fire man lol
monkey  How the fuck is it not related to anorexia nervosa is beyond me.
... tea-cats-biscuits made a comment on nbme24/block1/q#28 (A 32-year-old woman comes to the physician because...)
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submitted by tea-cats-biscuits(66)

Mast cells degranulate, producing histamine which attracts eosinophils. The early stage of an allergic reaction is mast cell mediated, but the late stage (including mucus production) is mediated by eosinophils.

atstillisafraud  Thanks for a good answer. This question made me feel like I was taking T21 pills
... lsmarshall made a comment on nbme24/block1/q#20 (Immediately after a spontaneous vaginal delivery, a...)
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submitted by lsmarshall(191)

Patient has Spina bifida occulta which is a neural tube defect (failure of fusion of the neuropores). Sclerotomes are the part of each somite in a vertebrate embryo giving rise to bone or other skeletal tissue. Since a part of this patient's spina bifida included "abscense of spinous process" then a sclerotome was involved. Knowing that neural tube defects are an issue with fusion should be enough to get to the right answer.

If the notochord failed to develop then the entire CNS would not develop as the notochord induces formation of neural plate.

If the neural tube failed to develop then the whole CNS would not have developed.

Yolk sac is irrelevant to this patient.

When neural crest cell it has different outcomes in different tissues. Failure of neural crest to migrate in heart can cause Transposition of great vessels, Tetralogy of Fallot, or Persistent truncus arteriosus. Failure of neural crests to migrate in GI can cause Hirschsprung disease (congenital megacolon). Treacher Collins Syndrome can occur when neural crest cells fail to migrate into 1st pharyngeal arch. Neural tube defects has nothing to do with failure of neural crest migration though.

sympathetikey  Exactly. I knew it had to due with fusion of the neuropores but had never heard of sclerotomes. Thanks for the explanation.
... atstillisafraud made a comment on nbme24/block3/q#42 (Which of the following terms best describes the...)
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submitted by atstillisafraud(50)

I like this question because it reminds me that examiners think objects can exist in 2 dimensions.

... tissue creep made a comment on nbme24/block3/q#49 (A 20-year-old woman with asthma comes to the...)
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submitted by tissue creep(25)

The poodle is hypoallergenic, and a 10/10 good boy.

... m-ice made a comment on nbme24/block2/q#18 (A 68-year-old man has loss of pain and temperature...)
 +12  upvote downvote
submitted by m-ice(122)

The patient has loss of pain and temperature on the right side of his face. Sensation of the face is ipsilateral, so the issue must be on the patient's right side, which we can confirm by knowing that sensation of the body is contralateral, and he has lost left sided pain and temperature of the body.

Pain and temperature sensation of the body is part of the spinothalamic tract, which always runs laterally through the brainstem. This can be confirmed by remembering that sensation to the face also runs laterally through the brainstem. So, we can confirm this is a right sided lateral brainstem issue.

The loss of gag reflex and paralysis of the vocal cords imply impairment of cranial nerves IX and X, both of which localize to the medulla. Therefore, the answer is right dorsolateral medulla.

duat98  You're a good man.
charcot_bouchard  You must be handsome too
... atstillisafraud made a comment on nbme24/block3/q#35 (A 4-year-old girl has a history of multiple bone...)
 +12  upvote downvote
submitted by atstillisafraud(50)

Thank you NBME for the high quality pictures. It makes these exams stress free and enjoyable.

sympathetikey  Feels bad man.
zoggybiscuits  Those Sclera sure look blue. wow.
yotsubato  the same girl shows up on so many NBME exams its not even funny. Its just like that poor kidney that's cut in half that shows up in all kidney questions.
... sattanki made a comment on nbme24/block4/q#49 (A 27-year-old man sustains a spinal cord transection...)
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submitted by sattanki(31)

Apparently there is a completely separate spinal cord reflex where direct penile stimulation leads to an erection. This reflex only needs an intact arc in S2-S4, so as long as this region is not injured, an erection can still occur. However, with transection at C8, then the psychogenic erection reflex cannot occur, as this requires descending fibers from the cortex.

lsmarshall  Just saw a good summary of nerves/vessels involved saying, "pelvic parasympathetic fibers from S2-S4 can cause cavernous arteriole vasodilation via the cavernous nerve without of central stimulation."
seagull  S2-3-4 keeps the penis off the floor
drdoom  Modifying @seagull into iambic pentameter: “S2, S3, and Number 4 / keeps the big ole penis / off the floor”
... neonem made a comment on nbme24/block4/q#40 (A 25-year-old woman is brought to the emergency...)
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submitted by neonem(251)

This patient isn't hypoventilating, they're HYPERventilating, hence the PCO2 < 40 mm Hg.

Let's walk it backwards: They are hyperventilating to compensate for the metabolic acidosis caused by widespread hypoxia. Hyperventilating allows you to blow off more CO2.

Why are they hypoxic? The person is hypoxic due to inflammation and acute respiratory distress syndrome from the pneumonia. All the cytokines from the inflammatory cells cause increased pulmonary capillary leakage, which blocks up the alveolar membrane so that O2 can't get through to the blood.

Why do they have metabolic acidosis in the first place? No oxygen --> no electron transport chain and no TCA --> lactic acidosis.

... drdoom made a comment on nbme24/block2/q#48 (The breakdown of dipeptides and tripeptides to free...)
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submitted by drdoom(185)

The duodenal lumen (and pancreatic proteases like CHYMOTRYPSIN) is the site where pancreatic enzymes (“endopeptidases”) cleave large polypeptides into smaller bits (=dipeptides,tripeptides). It is at the BRUSH BORDER where the smallest kinds of peptides (dipeptides,tripeptides) are broken down into their amino acids, which finally can be co-transported with Na+ into the intestinal cell.

I think about it this way:

  • stomach acid denatures and “opens up” proteins (without specific cleavage);
  • pancreatic enzymes then cleave denatured polypeptides into smaller bits;
  • brush border enzymes finally break down tiniest peptides into absorbable amino acids.
... brethren_md made a comment on nbme24/block1/q#40 (A 26-year-old man and his 25-year-old wife come to...)
 +11  upvote downvote
submitted by brethren_md(44)

Make a punnett square with a cross of B B+ and B B0; B+ represents 50% function while B0 represents 0% (null) function. So in this case, the husband would have a B B0 genotype while the wife has a B B+ genotype.

Cross of these two will result in the following genotypes; BB, BB0, BB+, B+B0 BB = 100% function, BB+ = 75% function, BB0 = 50% function, B+B0 = 25% function

So the answer will be 1 in 4 have a 25% function given the genotypes.

... lsmarshall made a comment on nbme24/block1/q#16 (A 32-year-old man is brought to the emergency...)
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submitted by lsmarshall(191)

Flexor digitorum profundus is responsible for flexion of DIP. Medial aspect of the muscle (which flexes the 4th and 5th digit) is supplied by the ulnar nerve (C8, T1). The lateral aspect (which flexes the 2nd and 3rd digit) is innervated by the median nerve specifically the anterior interosseous branch (C8, T1). So the question is describing a laceration damaging the nerve supply to the DIP flexor of the 2nd digit (index finger). This is saying the medial nerve is being damaged (C8 and T1; lower trunk roots).

Lumbricals (1st/2nd, median; 3rd/4th, ulnar) are a group of muscles that flex at the MCP joint, and extend PIP and DIP joints.

Could remember as 'flexor digitorum profundus is profoundly long' since tendons insert on DIPs. Compared to flexor digitorum superficialis whose tendon wraps around profundus' superficially but inserts on PIPs.

toupvote  This is dumb but I remember FDP is needed for picking while FDS is need for scratching the superficial layer of the skin
whoissaad  @lsmarshall Flexor digitorum superficialis inserts at the middle phalanges to be more specific.
... m-ice made a comment on nbme24/block3/q#38 (A 55-year-old man comes to the physician because of...)
 +10  upvote downvote
submitted by m-ice(122)

They explicitly state that the patient has been taking excess of his levothyroxine medication. Levothyroxine is the exogenous form of T4. Therefore, free T4 must be elevated. T4 is converted to T3 at most peripheral tissues, so T3 will also be elevated. Because the body has more thyroid hormone than needed, less TSH will be made, and the thyroid will be less active, taking up LESS iodine.

... neonem made a comment on nbme24/block3/q#4 (A 27-year-old man comes to the physician because he...)
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submitted by neonem(251)

I think the reason you need to inject gonadotropins in this case is because you need FSH and LH to produce sperm. FSH stimulates the sertoli cells, which line the seminiferous tubules and help the spermatogonia produce spermatocytes. Testosterone is a product of Leydig cells when they're stimulated by LH, so injecting testosterone would bypass that step but it wouldn't really help with spermatogenesis. However, injecting GnRH also doesn't doesn't really help because you need that pulsatile GnRH at night to make LH and FSH whereas long-acting GnRH analogs actually decrease LH and FSH production.

m-ice  Adding on to the answer above. I was stuck between the gonadotropin injections and clomiphene. But, clomiphene acts to increase activity of GnRH which then exerts its effects on the pituitary. The man in this question had his pituitary removed because of an adenoma. So, he needs the FSH and LH directly.
mousie  agree! Removal of the pituitary would case a deficit in Gonadotropins (LH, FSH) and therefore nothing to simulate the testes to make sperm... replacing the T with a patch would not stimulate the testes to make sperm and if his axis was intact (although its not) this would further down regulate the production of sperm. I eliminated Clomiphene because if he dosent have T to induce negative influence on the hypothalamus he will have increased GnRH and further increasing it with Clomiphene would not correct the deficit in Gonadotropins.
neonem  Oh duh... that makes much more sense. Thanks! P.s. I thought clomiphene was more of a fertility drug for women, since it blocks negative feedback of estrogen on the hypothalamus/pituitary. But in men the system is under feedback due to testosterone, not estrogen.
... lsmarshall made a comment on nbme24/block2/q#25 (A 35-year-old African American man comes to the...)
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submitted by lsmarshall(191)

Acral lentigious is most common type of melanoma in African Americans and is on the palms or soels. I guess the typical thinking of chest and back (sun exposed) is a little different in this type? Among all demographics; melanomas occur the majority of time on the limbs (~36% lower and ~19% upper); trunk is ~27%... So based on that and him being of African descent we can choose palms.

... lsmarshall made a comment on nbme24/block2/q#22 (A 3-month-old boy is brought to the physician...)
 +10  upvote downvote
submitted by lsmarshall(191)

Zellweger syndrome - autosomal recessive disorder of peroxisome biogenesis due to mutated PEX genes. Hypotonia, seizures, hepatomegaly, early death (within 1 year). β-oxidation of VLCFA happens in peroxisomes so the child seemingly having some sort of congenital metabolic disorder with elevated VLCFAs should have been enough to get the answer without knowing about Zellweger.

... neonem made a comment on nbme24/block4/q#29 (A 56-year-old man has a 3-year history of...)
 +9  upvote downvote
submitted by neonem(251)

Per Pathoma: early inherited cases of Alzheimer's dementia are associated with mutations in presenilin-1/presenilin-2, as well as Down's syndrome. Down's would be due to an extra chromosome 21, which carries the gene for amyloid precursor protein (APP). Extra APP is converted to A-beta amyloid and this forms extracellular neuritic plaques, a prominent feature of Alzehimer's.

Important to not confuse Amyloid A protein (one of the answer choices) with Amyloid precursor protein. Deposition of AA amyloid is more associated with chronic inflammatory states, malignancy, and Familial Mediterranean Fever. Beta-2 microglobulin is another amyloid association: dialysis-associated (deposits in joints)

... neonem made a comment on nbme24/block2/q#30 (A 35-year-old man with small cell carcinoma of the...)
 +9  upvote downvote
submitted by neonem(251)

Small cell carcinoma of the lung may produce paraneoplastic syndromes, of which ACTH and ADH are the more common subtypes. ACTH excess leads to excess stimulation on the adrenal cortex to produce cortisol, resulting Cushing's syndrome. Excess cortisol (normally a stress hormone) causes hypertension via potentiation of sympathetic stimulation on the vasculature. It can also cause hypokalemia by acting as a mineralocorticoid when in excess, saturating the ability of 11-beta-hydroxysteroid dehydrogenase (present in the renal tubules) to convert cortisol to cortisone, which doesn't act as a mineralocorticoid.

... tea-cats-biscuits made a comment on nbme24/block3/q#34 (An otherwise healthy 35-year-old man sustains a...)
 +9  upvote downvote
submitted by tea-cats-biscuits(66)

Because you are supine, there’s increased preload going back to your heart (no need to work against gravity, your blood isn’t pooling in your legs as much either). As a result, ANP is secreted due to RA stretch, leading to diuresis and a reduction of blood volume.

urachus  When the person is lying down (supine position), gravitational forces are similar on the thorax, abdomen and legs because these compartments lie in the same horizontal plane. In this position, venous blood volumes and pressures are distributed evenly throughout the body. https://www.cvphysiology.com/Cardiac%20Function/CF017
... seagull made a comment on nbme24/block1/q#11 (A 55-year-old man with type 1 diabetes mellitus...)
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submitted by seagull(413)

Another approach. Diabetes causes non-enzymatic glycosylation which may negatively impact the function of neurons mainly due to altered blood supply among other things. These glycosylate deposits typically occur peripherally at the legs. The only peripheral answer choice was a nociceptor in the legs. all the other answer choices are at least more centrally located with larger blood supplies.

Again, not perfect but a way to reason out this answer but it does work.

sam1  I believe this concept is referring to peripheral sensitization. Peripheral nerves that have sustained damage (such as through non-enzymatic glycosylation in DM) cause sensitization of their neighboring nerves, thus leading to lower thresholds for activation. This sensitization is thought to be accomplished through mediators such as PGE2.
sam1  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3701208/ ^ Section on peripheral sensitization
... lsmarshall made a comment on nbme24/block1/q#3 (A 52-year-old woman comes to the physician because...)
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submitted by lsmarshall(191)

The most direct path, and most likely path, for breast cancer to metastasize to the vertebra are the intercostal veins. This was on an earlier NBME test as well. Breast cancer will cause mixed, lytic and blastic lesions once in bone.

On an unrealated note; I finally came up with a decent way to remember lytic vs. blastic cancers in bone!

kIdneY and thYroId cause lYtIc

prostate > blastate > blastic

Two breasts > two types of lesions > B reast causes B oth

Two lungs > two types of lesions (depending on type of lung cancer)

small-cell lung > "small blasts"

non-small cell > lytic

artist90  VEINS: 1-Intercostal veins drain into Azygous vein which drains into SVC BUT some blood from this Azygous vein is also draining into BATSONS VERTEBRAL VENOUS PLEXUS how the breast cancer metastasizes to vertebral column. 2-Internal thoracic(mammary) vein drains directly into Brachiocephalic vein. 3-Lateral thoracic vein drains into Axillary vein which drains into Subclavian vein which drains into Brachiocephalic vein. ARTERIES ARE DIFFERENT: Subclavian artery----branches into---Internal thoracic(mammary) artery---Intercostal arteries. Internal thoracic artey is used for CABG if there is 1 vessel block.
... sympathetikey made a comment on nbme24/block4/q#33 (A 12-year-old boy is brought to the physician by his...)
 +8  upvote downvote
submitted by sympathetikey(301)

Everyone who got this question right is a cop. ༼⌐■ل͟■༽

... colonelred_ made a comment on nbme24/block3/q#34 (An otherwise healthy 35-year-old man sustains a...)
 +8  upvote downvote
submitted by colonelred_(45)

Looked it up and found that because you’re in a supine position for a long time you’re going to have increased venous return which leads to increased CO. This negatively feedsback on RAAS, leading to decreased aldosterone. As a result, you’re going to have increased diuresis which leads to decreased blood and plasma volume.

medstruggle  Doesn’t supine position compress IVC leading to decreased venous return? (This is the pathophys of supine hypotension syndrome.) There was a UWorld questions about this ...
tea-cats-biscuits  @medstruggle *Supine position* decreases blood pooling in the legs and decreases the effect of gravity. *Supine hypotension syndrome*, on the other hand, seems specific to a pregnant female, since the gravid uterus will compress the IVC; in an average pt, there wouldn’t be the same postural compression.
welpdedelp  this was the exact same reasoning I used, but I thought the RAAS would inactivate which would lead to less aldosterone and less sodium retention
yotsubato  You gotta be preggers to compress your IVC
nwinkelmann  Could you also think of it in a purely "rest/digest" vs "fight/fright/flight" response, i.e. you're PNS is active, so your HR and subsequently your CO is less? But the explanation given above does make sense. Also because I think just saying someone is one bed rest leaves a lot up for interpretation, maybe not with this patient because his pelvis is broken, but lots of people on bed rest aren't lying flat.... ?
urachus  wouldnt low aldosterone cause low plasma sodium? choice B
... tea-cats-biscuits made a comment on nbme24/block3/q#29 (Drug X is given to a 25-year-old normal subject....)
 +8  upvote downvote
submitted by tea-cats-biscuits(66)

Partial agonists have weak agonist activity on their own (thus in this case it causes HR to increase, b-adrenergic effect) but when an actual agonist is present (aka when you are exercising, you are producing NE and E that have full b-agonist effects), partial agonist actually have a mild antagonist effect (thus the heart rate decreases).

potentialdoctor1  Might be relevant to add that there are two beta-blockers that are actually partial beta-agonists (exert their blocking effects due to lesser effect when compared with endogenous catecholamines) ----> Pindolol and acebutolol
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