Serum desialotransferrin in the detection of alcohol abuse. Definition of a Tf index.

Different molecular forms of transferrin (Tf) have been separated in sera from alcoholics and controls by isoelectric focusing on ultrathin polyacrylamide gels using a semi narrow pH range. The main fraction focused at pH 5.4 (Tf5.4) and minor components appeared among controls at pH 5.7 (Tf5.7). This fraction was increased among alcoholics and was sometimes accompanied by a fraction focusing at pH 5.9 (Tf5.9). Fractions were quantified by densitometry following immunofixation. Significant differences in the ratios Tf5.4/Tf and Tf5.7/Tf between the groups were obtained, but no difference could be determined in the total Tf. We used the ratio Tf5.7/Tf5.4 called Tf index to distinguish alcoholics from controls. The sensitivity, the specificity and the global predictive value of this test were 0.82, 1 and 0.88 respectively. These results seems to indicate that the Tf index is more reliable for the detection of alcohol abuse than liver enzymes such as gammaglutamyl transferase (gamma GT) or glutamate dehydrogenase (GDH).