title: Elevated serum S-adenosylhomocysteine in cobalamin-deficient megaloblastic anemia.
abstract: Impaired methylation due to accumulation of S-adenosylhomocysteine (SAH) may contribute to the pathophysiology of cobalamin-deficient anemia. We assayed serum S-adenosylmethionine (SAM), SAH, total homocysteine (tHcy), and methylmalonic acid (MMA) in 15 subjects with cobalamin-deficient megaloblastic anemia and compared results with those of 19 subjects with anemia/pancytopenia due to other causes. Cobalamin-deficient subjects had a median hematocrit level of 20% and mean cell volume of 111.7 fL. The median serum cobalamin level was 37 pg/mL, MMA 3030 nmol/L, and tHcy 62.0 micromol/L. SAH was elevated in 13 of 15 subjects (median, 42 nmol/L) and the median SAM value was normal (103 nmol/L), but SAM/SAH ratio was low (2.5). The SAH was higher and SAM/SAH ratio was lower in cobalamin-deficient subjects compared with those with other anemias after excluding 4 patients with renal insufficiency. SAM concentrations were not low in cobalamin deficiency. Cobalamin injections corrected anemia, MMA, tHcy, SAM/SAH ratio, and SAH. Some hematologic variables were inversely correlated with SAH and cobalamin but not tHcy or MMA. In conclusion, serum SAH is elevated in cobalamin-deficient subjects with megaloblastic anemia and corrects with parenteral cobalamin therapy.
authors.affiliation: Department of Clinical and Toxicological Analysis, Pharmaceutical School, University of São Paulo, São Paulo 05508-900, Brazil.
authors.forename: Elvira M
authors.initials: EM
authors.lastname: Guerra-Shinohara
authors.forename: Olga E
authors.initials: OE
authors.lastname: Morita
authors.forename: Regina A
authors.initials: RA
authors.lastname: Pagliusi
authors.forename: Vera L
authors.initials: VL
authors.lastname: Blaia-d'Avila
authors.forename: Robert H
authors.initials: RH
authors.lastname: Allen
authors.forename: Sally P
authors.initials: SP
authors.lastname: Stabler
mesh_terms: D000328:Adult; D000368:Aged; D000749:Anemia, Megaloblastic / Q000097:blood*; D005260:Female; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics; D008875:Middle Aged; D012435:S-Adenosylhomocysteine / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000097:blood*
chemical_list: D006710:Homocysteine; D012435:S-Adenosylhomocysteine; D042965:Methylenetetrahydrofolate Reductase (NADPH2)