Cutaneous lesions and vitamin B12 deficiency

I must comment on your otherwise excellent and enjoyable article on vitamin B12 in the April issue of Canadian Family Physician which repeats the fallacy that the only treatment for pernicious anaemia is lifelong vitamin B12 injection. In fact, there is excellent high quality evidence that even in pernicious anaemia, sufficient Vitamin B12 is absorbed orally when a large enough dose is given. (Absorption occurs by diffusion even in the total absence of intrinsic factor.)

Some experts recommend parental B12 for neurological complications of B12 deficiency and multiple parenteral doses to replenish the body stores. In symptomatic individuals, it is also not unreasonable to give one parenteral dose at the same time as you start oral treatment. However, in neither state is it necessary to continue life-long injection treatments.

In an individual lacking intrinsic factor (or any other form of malabsorption) the amount of B12 passively absorbed from 500 micrograms orally a day is equivalent to a 1,000 microgram injection monthly.

Regarding dosing: The daily requirement of B12 is 2.5 micrograms. If 1% of a 500 mcg dose is absorbed, the absorbed amount equals 5 mcg (double the daily RDA). I usually prescribe 1,000 mcg B12 a day which is more than sufficient & allows for the occasional missed dose.

Once treatment has commenced, it is not necessary to check serum levels of B12. I have occasionally done so and the levels are invariably in the high physiologic range or higher.

As a GP, I often have to send this evidence to consultants, who attempt to return my patients on oral B12 to injection treatment. In an age of reduced patient and physician time with financial strains on the system, this simple change to oral treatment is beneficial.

I have appended an abbreviated list of references. Space precludes listing all pertinent references. They start in 1948 and continue until at least 2006.

In a recent Cochrane review, the authors stated, "Vitamin B12 is rarely prescribed in the oral form in most countries,other than Canada and Sweden, where such replacement recently accounted for 73% of the total vitamin B12 prescribed. Possible reasons for doctors not prescribing oral formulations include unawareness of this option or concerns regarding effectiveness due to unpredictable absorption." 1

REFERENCES

1 Vidal-Alabal et al Evidence-based Medicine 2006;11(1):9.

OTHER REFERENCES

Nyholm E. Turpin P. Swain D. Cunningham B. Daly S. Nightingale P. Fegan C. Oral vitamin B12 can change our practice. Postgraduate Medical Journal 2003;79(930):218-20.

Middleton J and Wells W. Vitamin B12 injections: considerable source of work for the district nurse. Br Med J 1985;290:1254 -1255.

Elia M. Oral or parenteral therapy for B12 deficiency.Lancet 1998; 352:1721-1722

Lederle FA. Oral cobalamin for pernicious anemia. Medicine's best kept secret? J Am Med Assoc 1991; 265:94-95.

Van Walraven C, Austin P, Naylor CD. Vitamin B12 injections versus oral supplements. How much money could be saved by switching from injections to pills? Can Fam Physician 2001; 47:79-86.

Spies T, Stone R, Lopez G, Milanes F, Toca R, Aramburu T. Vitamin B12 by mouth in pernicious and nutritional macrocytic anaemia and sprue. Lancet 1949;2:454-456.

Ross G, Mollin D, Cox E, Ungley C. Hematologic responses and concentration of vitamin B12 in serum and urine following oral administration of vitamin B12 without intrinsic factor. Blood 1954;9:473- 488.

Ungley C. Absorption of vitamin B12 in pernicious anaemia. I. Oral administration without source of intrinsic factor. Br Med J 1950;2:905- 908.

Berlin H, Berlin R, Brante G. (1968) Oral treatment of pernicious anemia with high doses of vitamin B12 without intrinsic factor. Acta Med Scand 1968;184:247-258.

Oral High-dose Cyanocobalamin-A Contagious Concept Norberg B. Rondel. Available at http://www.rondellen.net, 2001 (accessed 03 March 2004).

Lederle FA. Oral cobalamin for pernicious anemia: back from the verge of extinction. J Am Geriatr Soc 1998;46:1125-1127.

Vidal-Alaball J, Butler CC, Cannings-John R, et al. (2005) Oral vitamin B12 versus parenteral vitamin B12 for vitamin B12 deficiency. The Cochrane Database of Systematic Reviews issue 3.