Do you recommend starting with oral or intramuscular B12 supplementation in patients with newly diagnosed deficiency?

Good question - the answer has some nuances. When making this decision, I think about two things: 1) The severity of the deficiency/urgency of repletion and 2) the likely etiology of the deficiency.

Regarding #1, if a patient has symptomatic anemia or neuropsychiatric symptoms, regardless of etiolog...