Evaluation of the diagnostic performance of the Boehringer Mannheim CEDIA LSD assay

The precision and the diagnostic performance of the Boehringer Mannheim CEDIA DAU LSD assay was evaluated. The assay was performed in the semi-quantitative mode on a Hitachi 917 analyzer. Within-run coefficients of variation (CVs) of the semiquantitative values for 0.25 and 1.0 ng/mL were 11.2 and 6.2%, respectively. Day-to-day CVs for the same concentrations were 12.6 and 8.6%. We analyzed 318 urine samples by CEDIA, DPC Coat-A-Count RIA and Behring EMIT II. Confirmation was performed by GC-MS, after extraction on Bond Elut Certify columns. Two hundred sixty-three samples were negative by all methods. Twenty-five samples were positive by all immunoassays, 19 of which were confirmed by gas chromatography-mass spectrometry (GC-MS). One sample was falsely negative by CEDIA. Three samples were positive by EMIT and CEDIA, but negative by RIA and GC-MS. Twenty-six samples were positive by EMIT alone, but they were not confirmed by GC-MS. The LSD CEDIA assay seems to be less specific than DPC RIA but more specific than the EMIT LSD assay.