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NBME 21 Answers

nbme21/Block 1/Question#35

A 7-year-old boy is brought to the physician by his ...

Increased blood lead

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 +7  upvote downvote
submitted by pparalpha(23),

Lead Toxicity :

Causes: disruption of heme synthesis via inhibition of ALA (aminolevulinate dehydratase)


A: Anemia

B: Basophilic stippling

C: Colic

D: Diarrhea

E: Encephalopathy

F: Foot drop

G: Gum deposits/growth retardation/gout

H: HTN and hyperurecemia

Other answers:

Zinc deficiency:

Causes: low intake, Crohn's disease

Findings: immune dysfunction, impaired wound healing (for the remodeling phase of wound healing, zinc is needed by metalloproteinases to break down type III collagen), hypogonadism, diarrhea, dermatitis, alopecia, abnormal taste and smell

Excess is rare... but can lead to n/v/d and abdominal pain

Magnesium deficiency:

Causes: congenital, polyuria, malnutrition, laxative abuse

Findings: tetany, premature ventricular contraction, increased QT interval

B12 deficiency:

Causes: vegan diet, pernicious anemia, pancreatic issues, gastric bypass surgery, malabsorption (Crohn, sprue), Diphyllobothrium lactum/tapeworm infection

Findings: macrocytic, megaloblastic anemia, neuro symptoms, increased homocysteine and MMA levels in serum

Increased Vitamin D:

Causes: granulomatous disease (sarcoidosis)

Findings: bone resorption, too much calcium, loss of appetite, stupor

this patient presents with hypochromic anemia, it cannot be hypomagnesemia because it doesnt cause anemia, cannot be B12 because it would be megaloblastic, cannot be vitamin D because its not related to hypochromic anemia, and zinc is associated with iron deficiency anemia, but as a deficiency. Also, lead poisoning inhibits ferrochetalase, it looks like an iron deficiency anemia but since theres no other logical option it has to be the answer here


 +0  upvote downvote
submitted by nor16(11),

cns problem, anemia (hypo) and kidney problem.

Finally only lead can cause all of it