Vitamin B12 Deficiency

Question 1

What are the risk factors for vitamin B12 deficiency? List three.

Answer 1

Decreased ileal absorption (e.g. Crohns disease, ileal resection)
Decreased intrinsic factor (atrophic gastritis, pernicious anemia, postgastrectomy syndrome)
Inadequate intake (alcohol abuse, vegans/vegetarians) 
Prolonged medication use (histamine h2 blocker or PPI more than 12 months or metformin for more than 4 months)

Pernicious anemia = autoimmune process that reduces available intrinsic factor

Question 2

What are the clinical manifestations of vitamin B12 deficiency? List 4.

Answer 2

Cutaneous - skin hyperpigmentation
GI - glossitis
Hematologic - can affect all cell lines, megaloblastic anemia most common
Neuro/psychiatric - loss of proprioception and vibratory sense, areflexia, peripheral neuropathy, cognitive impairments olfactory impairment

Question 3

What is the treatment of vitamin B12 deficiency?

Answer 3

Oral vitamin B12 therapy

IM injections of cyanocobalamin

Question 4

What is the treatment regimen if there is B12 deficiency and a neurological deficit?

Answer 4

Injections qother day up to 3 weeks or until no further improvement is noted

Question 5

Explain how vitamin B12 is absorbed

Answer 5

Coabsorbed with intrinsic factor, a product of the stomach parietal cells in the terminal ileum after being extracted by gastric acid

Question 6

What medications increase the risk of B12 deficiency?

Answer 6

Histamine H2 blockers and PPI x 12 months

Metformin x 4 months

Question 7

What are the symptoms of B12 deficiency?

Answer 7

Easily fatigued with exertion
Palpitations
Skin pallor