B vitamin 2

Question 1

A blood smear from an alcoholic shows macrocytosis. Lab tests show elevation of homocysteine but not methylmalonic acid. Dx?

Answer 1

Folate deficiency

Question 2

Lab tests show elevation of homocysteine and methylmalonic acid. Dx?

Answer 2

B12 difficiency

Question 3

Lab tests show elevation of homocysteine and methylmalonic acid. Explain why this patient would have parasthesis

Answer 3

degeneration of dorsal columns, lateral corticospinal tracts, and spinocerebellar tracts:

Question 4

What lab values would you expect to see?

What Vitamin is deficient?

What MCV value would you expect?

Answer 4

Macrocytic, megaloblastic anemia; hypersegmented PMNs

Increased serum homocysteine and methylmalonic acid levels, along with 2° folate deficiency.

MCV > 100 fL Due to defect in DNA synthesis

Question 5

Malabsoprtion Causes of B12 difficiency:

lack of intrinsic factor (eg, pernicious anemia, gastric bypass surgery),

absence of terminal ileum (surgical resection, eg, for Crohn disease), or insufficient intake (eg, veganism).

Answer 5

malabsorption

(eg, sprue, enteritis, Diphyllobothrium latum, achlorhydria, bacterial overgrowth, alcohol excess),

Question 6

Causes of B12 difficiency via Lack of intrinsic factor

Answer 6

(eg, pernicious anemia, gastric bypass surgery),

Question 7

Causes of B12 difficiency via absence of terminal ileum

Answer 7

surgical resection, eg, for Crohn disease), or insufficient intake (eg, veganism).