Molecular weight: 176.13
Oxidized form: dehydroascorbic acid
Specimen types:
(1) leukocyte-related (correlates with body stores but may not be readily available since the assay is technically difficult)
(2) plasma (readily available but may reflect recent intake rather than body stores)
(3) urine after oral load (a deficient patient will not excrete the vitamin C in the urine after oral dosing)
Factors affecting levels:
(1) recent intake
(2) oxidation after collection
(3) improper storage if not tested immediately
Analytical methods:
(1) HPLC
(2) photometric (oxidation with 2,4-dintirophenylhydrazine or 2,4-dichlorophenolindophenol)
(3) fluorometric (ascorbate oxidase with o-phenylene diamine)
Results:
(1) Results for levels within leukocytes are reported as µg per 10^7 leukocytes or fmol (femtomol, 10^(-15) mol) per leukocyte (1 µg per 10^7 leukocytes = 0.0568 fmol per leukocyte)
(2) Plasma levels are reported in mg/dL or µmol/L (conversion factor for CU to SIU is 56.78)
