B12 Deficiency Anemia

Question 1

Vitamin B12

Answer 1

• water soluble vitamin

- needed for DNA synthesis, RBC production, maintaining CNS function

Question 2

3 Major Causes of B12 Deficiency

Answer 2

• inadequate intake
• decreased absorption (may be caused by H2RA or PPI, metformin)
• inadequate utilization

Question 3

Signs and Sxs of B12 Deficiency

Answer 3

• neuro: peripheral neuropathy, paresthesias, diminished vibration sense, ataxia, weakness
• neuropsych: irritability, dementia, depression
• glossitis, dysphagia, anorexia

Question 4

Lab Findings of B12 Deficiency

Answer 4

• MCV > 100 (macrocytic)
• mild leukopenia and thrombocytopenia
• peripheral smear: macrocytosis w/ hypersegmented PMN leukocytes and oval macrocytes
• low retic, B12, Hct

Question 5

Oral B12 Therapy

Answer 5

• 1-2 mg PO qday as effective as IM

- higher doses needed for pernicious anemia or cobalamin deficiency due to ileal reseection

Question 6

CI to Oral B12 Therapy

Answer 6

• inability to take PO meds
• diarrhea
• vomiting

Question 7

Parenteral B12 Therapy

Answer 7

• cyanocobalamin 1000 mcg qday x1 week
• then 1000 mcg qweek until hgb/hct normalizes
• then 100 mcg q month

Question 8

What can be used for pts in remission after IM B12 therapy who have no nervous system involvement?

Answer 8

• nasal spray q week

- no advantage over PO and more expensive

Question 9

Monitoring in B12 Deficiency

Answer 9

• rapid response
• reticulocytosis 2-5 days
• hgb starts to rise; leukocytes and platelets normalize at 1 week
• CBC and B12 1-2 months after tx start and 3-6 months thereafter for surveillance

Question 10

AEs of B12 Therapy

Answer 10

• hyperuricemia
• hypokalemia
• fluid retention
• rebound thrombocytosis
• anaphylaxis w/ parenteral administration