Assay for sulfhydryl amino acids and methods for detecting and distinguishing cobalamin and folic acid deficency
AssigneeUniversity Patents, Inc.
InventorsRobert H. Allen, Sally P. Stabler, John Lindenbaum
Life of this patent
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Abstract
Method for determining levels of sulfhydryl amino acids, particularly total homocysteine levels in samples of body tissue from warm-blooded animals, methods of detecting cobalamin and folic acid deficiency using an assay for total homocysteine levels, and methods for distinguishing cobalamin from folic acid deficiency using an assay for total homocysteine levels in conjunction with an assay for methylmalonic acid.
Claims34
A method of assaying for the amount of one or more sulfhydryl amino acid species present in a given sample, said method comprising:
- (a) combining said sample with an internal reference standard comprising a known amount of each sulfhydryl amino acid species to be assayed, labelled with a suitable marker;
- (b) adding sufficient reducing agent to insure randomization of the labelled and unlabelled sulfhydryl amino acids present;
- (c) measuring the relative amounts of labelled and unlabelled sulfhydryl amino acid present for each species with a mass spectrometer;
- (d) calculating the ratio of labelled to unlabelled sulfhydryl amino acid present for each species;
- and
- (e) deriving the amount of unlabelled sulfhydryl amino acid present for each species in said given sample.
A method for detecting a deficiency of cobalamin or folate in warm-blooded animals comprising the steps of:
- assaying a body fluid for an elevated level of total homocysteine;
- and
- correlating an elevated level of total homocysteine in said body fluid with a deficiency of cobalamin or folate.
A method for detecting a deficiency of cobalamin, folate, or both in warm-blooded animals and distinguishing therebetween comprising assaying body fluids for the presence of elevated levels of total homocysteine and methylmalonic acid, wherein normal levels of total homocysteine indicate no cobalamin or folic acid deficiency, elevated levels of total homocysteine and methylmalonic acid indicate cobalamin deficiency, and elevated levels of total homocysteine combined with normal levels of methylmalonic acid indicate folic acid deficiency.
Dependencies are inferred from the claim text.