Ciba Corning ACS:180 Direct Total Testosterone Assay Can Be Used on Female Sera

Abstract

We were intrigued by the article by Fitzgerald and Herold (1), which compared the fully automated, nonisotopic, direct (i.e., no serum purification step performed before analysis) assay of total testosterone used in the Ciba Corning Diagnostics ACS:180 instrument (Chiron Diagnostics, Medfield, MA) with a chemical ionization GC-MS method and with a manual, coated-tube, direct RIA [Coat-A-Count; Diagnostic Products Corp. (DPC), Los Angeles, CA]. The advantages of an accurate, fully automated, nonisotopic testosterone method over a manual RIA, with or without a purification step, are obvious. The authors observed excellent correlation ( r = 0.99) between testosterone values obtained with the ACS:180 vs GC-MS of male sera (1). However, the poor correlation ( r = 0.56) between testosterone values obtained with the ACS:180 vs GC-MS of female sera, prompted them to suggest “that Fuqua’s recommendation of a purification step before immunoassay analysis should be extended to include all female specimens, since ACS and DPC immunoassays did not agree with GC-MS” (1). In women, measurement of the serum testosterone concentration is useful in evaluating hirsutism, alopecia, and menstrual disorders. With assays by the ACS:180 method/instrument, hirsute women have been shown to have testosterone concentrations 0.7–1.4 times the upper limit (2.5 nmol/L) of the reference interval (2). We obtained good agreement between testosterone values quantified with the ACS:180 vs the DPC method (DPC testosterone = 0.974ACS + 0.357; r = 0.969; n = 35) used routinely in our laboratory. Because of the advantages of the fully automated ACS:180 system, we changed to this method. The recommendation by Fuqua, endorsed by Fitzgerald and Herold (1), however, prompted us … bAuthor for correspondence.