CARBOHYDRATE-DEFICIENT TRANSFERRIN AND FALSE-POSITIVE RESULTS FOR ALCOHOL-ABUSE IN PRIMARY BILIARY-CIRRHOSIS - DIFFERENTIAL-DIAGNOSIS BY DETECTION OF MITOCHONDRIAL AUTOANTIBODIES

Primary biliary cirrhosis (PBC) is one of the few nonalcohol-induced l iver pathologies that causes false positives in assays of carbohydrate -deficient transferrin (CDT) for diagnosing alcohol abuse. CDT was qua ntified by isoelectric focusing-immunoblotting-laser densitometry (IEF -IB-LD) analysis of serum from 117 women: 57 PBC patients, 20 alcohol abusers, and 40 healthy donors. Only 5% (3 of 57) of PBC patients were positive at the densitometric cutoff value chosen (> 90% specificity) . Serum samples from 15 PBC patients were further evaluated by IEF-IB- LD and CDTect(R) chromatography-RIA. Receiver-operating characteristic (ROC) analysis showed that IEF-IB-LD better discriminated between PBC and alcohol abuse than CDTect did. By ROC analysis, mitochondrial aut oantibodies to pyruvate dehydrogenase antigen M2 detected by enzyme im munoassay yielded optimal test performance for diagnosing PBC. Of six patients falsely positive for CDT by CDTect, five (83%) tested M2-posi tive. Thus, abnormal CDT results should be further evaluated by mitoch ondrial antibody testing in patients with findings compatible with PBC .