2–5 µg of B₁₂ IM for 8–15 d.

Five persons who were given 3 µg/d of B₁₂ for 15 d had a reticulocyte response that was not followed by a further response to more B₁₂. This amount allowed restoration of status.

1 mg of slow-release B₁₂ IM every 2 or 3 mo for at least 8 y. The less-frequent dose was equivalent to 1.7 µg of B₁₂/d.^b

Serum B₁₂ values were well above the cutoff of 180 pmol/L (250 pg/mL) early in the study and complete hematological remission occurred in all.

35 received 1 mg of B₁₂ IM every 5–6 mo, 6 received it every 3–4 mo, 3 received it every 2 mo. Smallest and most frequent dose was equivalent to 0.8–1.0 µg of B₁₂/d.^d

From total group analyses, 14 subjects had mild hematological relapse on 42 occasions; 34 subjects had at least one abnormal serum B₁₂ or metabolite value on 146 occasions when there was no evidence of hematological relapse.

2.0 µg oral dose of B₁₂ Co⁶⁰ given with intrinsic factor.

With 70% absorption, complete hematological response, and adequate plasma B₁₂ concentration, 1.4 µg of absorbed B₁₂ met the requirements of two-thirds of the subjects.

10 µg of B₁₂ given IM every 2 wk or 20 µg of B₁₂ given IM monthly for 10 y (equivalent average of 0.7 µg/d).

None of the subjects maintained serum B₁₂ concentration above the 180 pmol/L (250 pg/mL) lower limit of normal for the Lactobacillus leichmannii method.

0.1 µg/d of cyanocobalamin IM for 10 d; 0.1 µg/d of coenzyme B₁₂ IM for 10 d.

Posttreatment serum B₁₂ was 85 pmol/L (60 pg/mL) (range, 20–200 pmol/L [14–139 pg/mL]); 6 of 8 had reticulocyte response, but macrocytosis persisted in all and hypersegmentation did in many. In some, neurological abnormalities progressed until at least 1 µg of B₁₂ was given daily. All but one were later given higher doses of B₁₂.