Repeated USMLE Questions Step 2 CK- Review- 51

Q- A 30-year-old woman presents with chronic diarrhea, bloating, and weight loss. Laboratory testing reveals iron deficiency anemia. Symptoms improve on a gluten-free diet.

Which of the following antibodies is most specific for this condition?

A- Anti-centromere antibodies

B- Anti-dsDNA antibodies

C- Anti-endomysial antibodies

D- Anti-mitochondrial antibodies

C- Anti-endomysial antibodies- Celiac disease is associated with anti-endomysial and anti–tissue transglutaminase antibodies and improves with gluten avoidance.

 

Q- A 58-year-old man presents with progressive fatigue and exertional dyspnea. Physical examination reveals pale conjunctiva. Laboratory studies show hemoglobin 8.9 g/dL, MCV 105 fL, and hypersegmented neutrophils on peripheral smear.

Which of the following is the most likely underlying cause?

A- Chronic inflammation

B- Iron deficiency

C- Thalassemia

D- Vitamin B12 deficiency

D- Vitamin B12 deficiency- Macrocytic anemia with hypersegmented neutrophils is characteristic of megaloblastic anemia, most commonly due to vitamin B12 or folate deficiency.

 

Q- A 65-year-old woman presents with sudden vision loss in her right eye. Fundoscopic exam shows a pale retina with a cherry-red spot.

What is the most likely diagnosis?

A- Acute angle-closure glaucoma

B- Central retinal artery occlusion

C- Central retinal vein occlusion

D- Retinal detachment

B- Central retinal artery occlusion- Cherry-red spot with acute painless vision loss is classic for central retinal artery occlusion, an ophthalmologic emergency.

 

Q- A 72-year-old man presents with acute confusion after being treated for pneumonia. Labs reveal sodium 118 mEq/L with low serum osmolality and inappropriately concentrated urine.

What is the most likely diagnosis?

A- Adrenal insufficiency

B- Dehydration

C- Diabetes insipidus

D- Syndrome of inappropriate ADH secretion (SIADH)

D- Syndrome of inappropriate ADH secretion (SIADH)- SIADH causes euvolemic hyponatremia with low serum osmolality and concentrated urine, often triggered by pulmonary disease.

 

Q- A 40-year-old woman presents with episodic flushing, diarrhea, and wheezing. CT scan reveals a mass in the ileum.

Which of the following substances is most likely elevated?

A- Gastrin

B- Histamine

C- Serotonin

D- Vasoactive intestinal peptide

C- Serotonin- Carcinoid syndrome causes flushing, diarrhea, and wheezing due to excess serotonin secretion, commonly from ileal tumors.

 

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