Low serum cobalamin in disorders of cobalamin transport (letter)

Mild transcobalamin I (haptocorrin) deficiency and low serum cobalamin concentrations.

BACKGROUND Low cobalamin concentrations are common, but their causes are often unknown. Transcobalamin I/haptocorrin (TC I/HC) deficiency, viewed as a rare cause, has not been examined systematically in patients with unexplained low serum cobalamin. METHODS Total TC I/HC was measured by RIA in three subgroups of 367, 160, and 38 patients with different categories of low cobalamin concentratio...

Ins and outs of cellular cobalamin transport.

Evaluation of indicators of cobalamin deficiency defined as cobalamin-induced reduction in increased serum methylmalonic acid.

BACKGROUND Early detection of cobalamin deficiency is clinically important, and there is evidence that such deficiency occurs more frequently than previously anticipated. However, serum cobalamin and other commonly used tests have limited ability to diagnose a deficiency state. METHODS We investigated the ability of hematological variables, serum cobalamin, plasma total homocysteine (tHcy), s...

Cobalamin-responsive disorders in the ambulatory care setting: unreliability of cobalamin, methylmalonic acid, and homocysteine testing.

Early recognition of cobalamin (Cbl)-responsive disorders in the ambulatory care setting is essential to prevent irreversible neurologic deficits. However, diagnostic algorithms using Cbl, methylmalonic acid (MMA), and homocysteine (HCys) measurements reflect studies in academic centers, and their negative predictive values have not been established. Thus, records of 456 ambulatory patients eva...

Cobalamin Binding and Cobalamin-Dependent Enzyme

This work was presented in part at the meeting ofthe American Society of Human Genetics, San Diego, Calif., October 1977. Dr. Mellman and Dr. Willard are recipients of traineeships from the National Institutes of Health (T01-GM 02299). Dr. Mellman's present address is Laboratory of Cellular Physiology and Immunology, The Rockefeller University, New York 10021. Received for publication 18 May 19...