any immunoassay, with or without an extraction and a purification step, requires validation by a definitive or reference method before being considered a gold standard (2 ).We have not made an arbitrary statement that extraction/chromatography RIAs for testosterone do not work. Our point is that there are no convincing data showing that they do work. The only existing reports, from two independent sources (1, 5 ), that compared extraction/ chromatography RIA with gas chromatography-mass spectrometry show that there are considerable problems with these analyses. Until an extraction/chromatography RIA has been properly validated the results generated from such tests are subject to question.We appreciate the opportunity to further emphasize the need for proper validation of steroid immunoassays. Ciba Corning ACS:180 Direct total testosterone assay can be used on female sera.

Our data support a decision level of > 60 mmoL/L for confirmatory CF testing. A lower decision level will result in an unacceptable high rate of unnecessary confirmation testing.

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