Master the Boards USMLE Step 2CK Hematology Questions and answers 100% correct

Master the Boards USMLE Step 2CK - Hematology - Questions A 73-year-old man comes to the office with fatigue that has become progressively worse over the last several months. He is also short of breath when he walks up one flight of stairs. He drinks 4 vodka martinis a day. He complains of numbness and tingling in his feet. On physical examination he has decreased sensation of his feet. His hematocrit is 28% and his MCV is 114 fL (elevated). What is the most appropriate next step in management? A. Vitamin B12 level B. Folate level C. Peripheral blood smear D. Schilling test E. Methylmalonic acid level - Answer: C. Although a macrocytic anemia could be from B12 or folate deficiency, direct alcohol effect on the bone marrow, or liver disease, the first step is a peripheral smear. This is to detect hypersegmented neutrophils. Once hypersegmented neutrophils are seen, then you would get B12 and folate levels. A 73-year-old woman comes with decreased position and vibratory sensation of the lower extremities, a hematocrit of 28%, MCV of 114 fL, and hypersegmented neutrophils. Her B12 level is decreased, but near the borderline of normal. What is the most appropriate next step in the management of this patient? A. Methylmalonic acid level B. Anti-intrinsic factor antibodies C. Anti-parietal cell antibodies D. Schillings test E. Folate level F. Homocysteine level - Answer: A. USMLE Step 2 CK frequently tests the fact that while both B12 and folate deficiency increase homocysteine levels, only B12 is associated with an increased MMA. The B12 level can be normal in as many as a third of patients with B12 deficiency because the carrier protein, transcobalamin, is an acute phase reactant and can be elevated from many forms of stress such as infection, cancer, or trauma. When the story suggests B12 deficiency and the B12 level is equivocal, use an increased MMA level to confirm the diagnosis of vitamin B12 deficiency. Which of the following is a complication of B12 or folate replacement? A. Seizures B. Hemolysis C. Hypokalemia D. Hyperkalemia E. Diarrhea - Answer: C. Extremely rapid cell production in the bone marrow causes hypokalemia. There is no other condition in which cells are generated so rapidly that they use up all the potassium. Hyperkalemia from massive tissue or cellular breakdown has many causes. Hypokalemia from cell production is rare. When replacing B12 and folate, particularly if there is pancytopenia, cells in the marrow are produced so rapidly that the marrow packages up all the potassium, lowering the serum level. Observe and replace.