Vitamin B₁₂ Metabolism in Myelomatosis

Abstract

In 38 patients with myelomatosis the serum cobalamin varied from 34 pmol/l to 404 pmol/l, median 181.5 pmol/l, which is significantly lower than the levels in 22 control persons with range 173–535 pmol/l, median 265 pmol/l. In spite of low serum cobalamin no symptoms of vitamin B 12 deficiency could be demonstrated in any of the patients, except for the one patient who had a serum cobalamin of 34 pmol/l. Mean values for Hb, MCV, PCV, serum lactate‐dehydrogenase, adjusted red cell folate and nucleated neutrophil count were similar in a group of patients with a serum cobalamin below 160 pmol/l and a group of patients with higher serum cobalamin values. The decrease in serum cobalamin is due in part to a reduction in the major cobalamin binder (TC‐I) in serum. Measuring serum cobalamin in relationship to gastric acid secretion, we found a significantly higher frequency of hypo‐ and achlorhydria in patients with serum cobalamin below 160 pmol/l although the intestinal absorption of vitamin B 12 was normal by a Schilling test. Although our finding of low saturation of TC‐I in serum seems to demonstrate decreased vitamin B 12 content in the body in myelomatosis, the lack of evidence for a functional vitamin B 12 deficiency speaks against giving a supplement to patients with myelomatosis.