Evaluation of the measurement of prolactin in serum with Enzymun-Test System ES-600

The Enzymun-Test System ES-600 is a fully automated analyser for the Clinical Chemistry hormone laboratory. The Enzymun-Test prolactin, an enzyme immunoassay, is based on a sandwich technique using two monoclonal antibodies, one coated onto tubes and the other labelled with peroxidase. We have studied the measurement of prolactin concentration in serum and compared the results obtained with both this system and with the manual IRMA used in our laboratory. The within-day imprecision gave the following CV (n = 20): 6% at 64 mU/l, 1% at 379 mU/l and 2% at 1232.1 mU/l. The CV for between-day imprecision (n = 20) was 10%, 8% and 6%, respectively. The detection limit was 4 mU/l and linearity was demonstrated with geometric dilutions of a highly concentrated serum. We observed an average recovery of 104%, ranging 95.6%-110%. The calculated carryover was of 0.05%, and there was no trend in the measurements to indicate the occurrence of long series drift. In the study of interchangeability (Passing-Bablok regression test) we obtained a linear equation: y (ES-600) = 3.16 mU/l + 0.82 x (IRMA), with the confidence intervals (95%) a(-30.69, 21.53); b(0.73, 0.99); and a correlation coefficient of r = 0.98.