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USMLE® Step 1 questions

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USMLE® Step 1 style questions USMLE

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A 56-year-old man comes to the clinic with generalized fatigue and dyspnea on exertion that he noticed over the past month. He now becomes breathless after walking up a flight of stairs. He has also noticed numbness in his lower limbs over the last 2 weeks. Past medical history includes chronic pancreatitis. He has been drinking a pint of vodka daily for the past 25 years. Temperature is 37.0°C (98.6°F), pulse is 92/min, respirations are 19/min, and blood pressure is 135/85 mmHg. BMI is 20 kg/m2. He is alert, cooperative, and oriented to time, place, and person. Neurological examination reveals symmetrical peripheral neuropathy in a “stocking and glove” distribution with defective perception of touch and vibration sensation. Motor strength is 3/5 in the lower limbs and 5/5 in the upper limbs bilaterally. Symmetrical muscle wasting is noted in both lower limbs. Deep tendon reflexes are absent at the ankles bilaterally. On cardiac auscultation, a 3rd heart sound is heard, and the apical impulse is displaced to the 6th intercostal space. Romberg sign is negative. Laboratory investigations are shown below:

 Laboratory value  Result 
 Complete blood count 
 Hemoglobin  13 g/dL 
 Hematocrit  40% 
 Leukocyte count  5,000/mm3 
 Platelet count  150,000/mm3 
 MCV                 88 fL 

Serum methylmalonic acid levels are normal. This patient’s condition is most likely associated with which of the following impaired biological processes? 

External References

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Alcoholism p. 595

wet beriberi p. 714


cardiomyopathy p. 317

vitamin B1 deficiency p. 64

Dilated cardiomyopathy p. 317, 318, 481

wet beriberi p. 64

Dry beriberi p. 64


wet beriberi p. 64

Wet beriberi p. 64


Beriberi is a disease caused by a deficiency of thiamine (vitamin B1). This can be due to reduced intake, or a problem with thiamine absorption. Beriberi can exist as wet beriberi, which is when it mainly affects the cardiovascular system causing high-output heart failure with symptoms like dyspnea, and peripheral edema. There can also be dry beriberi, causing symptoms like wasting, and paralysis due to nerve damage. Dry beriberi usually presents with peripheral neuropathy, confusion, and nystagmus (involuntary eye movements).


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