The clinical value of measuring concentrations of methylmalonic acid in serum (S-MMA) as an aid in the diagnosis of cobalamin deficiency has recently aroused interest. In 58 healthy subjects, ages 40-68 years, we found a 0.95 reference interval of 0.05-0.37 mumol/L (mean 0.21, SD 0.094). In 33 of the subjects, who were studied further, day-to-day variation (SD) was 0.031 mumol/L. Intake of food...

Vitamin B12 deficiency and hyperhomocysteinemia are common in tropical developing countries. In prevalence study, among Indian population by Yajnik and colleagues, 67% of men had low vitamin B12 concentration and 58% had hyperhomocysteinemia [1]. Here, we report two patients with vitamin B12 deficiency presented with symptoms of schizophrenia and required very high doses of antipsychotic medica...

Vitamin B12 (cobalamin) deficiency is common in developing countries. Its dermatologic manifestations include hair and nail changes and glossitis. Cases of generalized hyperpigmentation associated with vitamin B12 deficiency have rarely been reported. Localized hyperpigmentation is less frequently described, affecting palms, soles, and flexural areas. We report a rare case of reversible melasma...

Imerslund-Gräsbeck syndrome (IGS) or selective vitamin B(12) (cobalamin) malabsorption with proteinuria is a rare autosomal recessive disorder characterized by vitamin B(12) deficiency commonly resulting in megaloblastic anemia, which is responsive to parenteral vitamin B(12) therapy and appears in childhood. Other manifestations include failure to thrive and grow, infections and neurological d...

In cobaiamin deficiency, inadequate DNA-thymine synthesis appears to resuit from decreased conversion of N5methyltetrahydrofolic acid to tetrahydrofo ic acid (THE). The N5-methyl THE conversion catalyzed by N5methyl THF-homocysteine methyltransferase requires a cobalamin coenzyme, presumed to be methylcobalamin (methyl-B12). In support of the above, in B12-deficient marrow cultures, methyl-B12 ...

BACKGROUND Diagnosing cobalamin (Cbl) deficiency as a cause of polyneuropathy (PN) is problematic, as the frequency of both disorders increases with age, and serum Cbl levels can be difficult to interpret. OBJECTIVES To identify unique clinical or laboratory features among PN patients with Cbl deficiency and to examine the role of testing of serum metabolite levels in the identification of Cb...

1. The isolated perfused rat liver and suspensions of isolated rat hepatocytes fail to form glucose from histidine, in contrast with the liver in vivo. Both rat liver preparations readily metabolize histidine. The main end product is N-formiminoglutamate. In this respect the liver preparations behave like the liver of cobalamin- or folate-deficient mammals. 2. Additions of L-methionine in physi...

Methionine synthase reductase (MSR) deficiency is an autosomal recessive disorder of folate/cobalamin metabolism leading to hyperhomocysteinemia, hypo- methioninemia and megaloblastic anemia. Deficiency in MSR activity occurs as the result of a defect in the MSR enzyme, which is required for the reductive activation of methionine synthase (MS). MS itself is responsible for the folate/cobalamin-...