The limited value of methylmalonic acid, homocysteine and holotranscobalamin in the diagnosis of early B12 deficiency

28/07/06

Disorders of Erythropoiesis • Brief Report

Andrew Goringe, Richard Ellis, Ian McDowell, Josep Vidal-Alaball, Christopher Jenkins, Christopher Butler, Mark Worwood

Treatment of B12 deficiency is important to prevent progressive neurological and/or hematologic disease but requires a secure diagnosis. The aim of this study was to evaluate second line tests of B12 status as prognostic indicators of a hematologic response to vitamin B12 therapy. Forty-nine patients referred with low, serum vitamin B12 concentrations were treated with intramuscular B12 and re-assessed after 3 months. Methylmalonic acid, homocysteine, holotranscobalamin and neutrophil hypersegmentation index were measured before and after treatment. Before treatment 27/49 patients were anemic or macrocytic of whom 15 had a clear hematologic response. All the tests had a similar prognostic accuracy. Symptomatic improvement did not correlate with hematologic response. Supplementary tests of vitamin B12 status were not significantly better than total serum B12 concentration as predictors of a hematologic response to vitamin B12 therapy.

Key words: vitamin B12 deficiency, B12 therapy, methylmalonic acid, homocysteine, transcobalamin, neutrophil hypersegmentation index.

Haematologica 2006; 91:231-234