Comparison of Bio-Rad %CDT TIA and CDTect as Laboratory Markers of Heavy Alcohol Use and Their Relationships with g-Glutamyltransferase

is used as a serum marker for heavy drinking. We compared a new Bio-Rad %CDT TIA assay with the CDTectTM assay; we also compared both to g-glutamyl-transferase (GGT) as markers of heavy drinking. Methods: Serum samples of well-defined alcoholics (n 5 404) and matched (age, race, and gender) social drinkers (204) from 10 clinical centers were assayed with both CDT assays. Both assays use microcolumn separa-tion after iron saturation, followed by enzyme immuno-assay (CDTect) or turbidimetric immunoassay (Bio-Rad %CDT). In the latter, CDT is expressed as a percentage of total transferrin. Results: The slope and intercept [95 % confidence inter-vals (CIs)] for linear regression of results obtained by the %CDT-TIA (as percentage) and CDTect (units/L) assay