Vitamin B12 Metabolism in Myelomatosis

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Abstract
In 38 patients with myelomatosis the serum cobalamin varied from 34-404 pmol/l, median 181.5 pmol/l, which is significantly lower than the levels in 22 control persons with a range of 173-535 pmol/l, median 265 pmol/l. In spite of low serum cobalamin no symptoms of vitamin B12 deficiency could be demonstrated in any of the patients, except for the 1 patient who had serum cobalamin of 34 pmol/l. Mean values for Hb, MCV [mean cell volume], PCV [packed cell volume], serum lactate dehydrogenase, adjusted red cell folate and nucleated neutrophil count were similar in a group of patients with 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, a significantly higher frequency of hypo- and achlorhydria was found in patients with serum cobalamin below 160 pmol/l, although intestinal absorption of vitamin B12 was normal by a Schilling test. Although the finding of low saturation of TC-I in serum seems to demonstrate decreased vitamin B12 content in the body in myelomatosis, the lack of evidence for a functional vitamin B12 deficiency speaks against giving a supplement to patients with myelomatosis.