WBR1083

Author	Chetan Lokhande
Exam Type	USMLE Step 3
Main Category	Primary Care Office
Sub Category	Gastrointestinal, Hematology
Prompt	A 45 year old long standing diabetic, on a vegan diet being treatment with oral hypoglycemic drugs, presents to your office with fatigue and tingling - numbness in his both feet. Physical examination revealed a bilateral loss of pinprick and vibration sense just above the ankles. However, both ankle jerks were present and brisk. Which of these the most likely cause of his symptoms?
Answer A	Diabetic neuropathy
Answer A Explanation	The first symptoms of diabetic neuropathy is loss of ankle jerk. Since this patient has ankle jerk brisk and present this cannot be diabetic neuropathy .
Answer B	Pernicious anemia
Answer B Explanation	Pernicious anemia presents is the loss of ability to absorb vitamin B12 (B12). It is the most common cause of adult B12 deficiency. Impaired absorption of vitamin B12 may be due to a loss of intrinsic factor or to a number of other conditions that decrease production of gastric acid, which also plays a part in the absorption of B12 from foods.
Answer C	Inadequate diet
Answer C Explanation	The patient is vegan and hence it might be a distractor for inadequate B12 in the diet. But there is no reason to believe that the patient is B12 deficient.
Answer D	Malabsorption
Answer D Explanation	A well known complication of metformin is Vit B12 malabsoption . Metformin when used chronically presents with peripheral neuropathy due to B12 malabsoption.
Answer E	Alcoholism
Answer E Explanation	Though alcoholics present with B12 and folate deficiency there is no history of alcohol in the question.
Right Answer	D
Explanation	Chronic metformin use for more than 10- 15 years cause Vit B12 deficiency by exhaustion of the stores. It presents as a peripheral neuropathy often misdiagnosed as diabetic neuropathy. The Other side efect of metformin is lactic acidosis. This B12 deficiency should be treated by stopping the offending agent and replenishing b12 stores. Educational Objective: References:
Approved	Yes
Keyword	Vit B12, Metformin, Diabetes mellitus
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