Immunoassays for Testosterone in Women: Better than a Guess?

Recent developments in the field of mass spectrometry have provided the accuracy and sensitivity to evaluate very-low-abundance steroids such as testosterone in female and pediatric patients. In this issue of Clinical Chemistry , Taieb et al. (1) present the most comprehensive evaluation of automated testosterone immunoassays to date. They compared 10 commercially available immunoassays with isotope-dilution gas chromatography–mass spectrometry (ID-GC/MS) and reached the inescapable conclusion that testosterone immunoassay results for specimens from females are inaccurate. Similar data have been reported for individual testosterone immunoassays previously (2), but Taieb et al. (1) are the first to show that for every commercially available testosterone assay studied, the values are in error—by a factor of 2 on average and in some cases by a factor of almost 5. Are assays that miss target values by 200–500% meaningful? Guessing would be more accurate and additionally could provide cheaper and faster testosterone results for females—without even having to draw the patient’s blood.By limiting all guesses to a narrow range, e.g., 2.04–2.44 nmol/L, the results would rarely be off by more than a factor of 3. Using a random number generator, we generated values close to the average female concentration measured by Taieb et al. (they were kind …