SERUM METHYLMALONIC ACID AND TOTAL HOMOCYSTEINE IN PATIENTS WITH SUSPECTED COBALAMIN DEFICIENCY - A CLINICAL-STUDY BASED ON GASTROINTESTINAL HISTOPATHOLOGICAL FINDINGS

We compared the sensitivity and specificity of the two metabolite test s, methylmalonic acid (MMA) and total homocysteine (Hcy) in serum, and serum cobalamin (Cbl) in patients referred to our hospital because of suspected cobalamin deficiency and a serum cobalamin value at the ref erring unit <200 pmol/L. All 111 patients included were investigated u sing upper gastrointestinal endoscopy with biopsy specimens taken from the gastric and duodenal mucosa to find a morphological basis for cob alamin malabsorption as well as the Schilling test for the validation of the serum tests, All patients were treated with cobalamin and new b lood samples were taken after 4 weeks. We found no difference in sensi tivity and specificity between serum MMA, Hcy, and Cbl in identifying patients with and without conditions compatible with cobalamin malabso rption. Elevated serum MMA and Hey were also found in about 15% of the group of patients with normal Schilling tests and without a morpholog ical basis for cobalamin malabsorption, Moreover, most patients in thi s group responded with decreased values of the metabolite tests follow ing cobalamin treatment, suggesting that neither elevated metabolites nor a decrease in these values following cobalamin treatment are speci fic for cobalamin deficiency. (C) 1997 Wiley-Liss, Inc.