Diurnal Variability and in Vitro Stability of Carbohydrate-deficient Transferrin

Abstract

Transferrin isoforms with pI values ≥5.7, known as carbohydrate-deficient transferrin (CDT), are present in increased concentrations in the serum of patients with current alcohol abuse. CDT has been found to be a specific and sensitive marker for detection and monitoring of high and continual alcohol consumption (1). The clinical performance of CDT has been studied using various techniques for analysis but also using various conditions for serum sample collection and sample storage. The biological (non-alcohol-influenced) variation over time has been found to be low (2). We have studied the diurnal variability of CDT and the effect of sample storage conditions in the commercial CDTect assays. Blood was collected by venipuncture and allowed to clot at room temperature. The serum samples were separated by centrifugation, and 1-mL portions were aliquoted into polypropylene tubes (Sarstedt). CDT was measured by duplicate determinations in CDTect® RIA or CDTect EIA (Pharmacia & Upjohn Diagnostics AB). Results are expressed as units per liter. In an evaluation performed on 76 serum samples …