Endocrine Abstracts

Introduction: The quality of testosterone assays has been a matter of debate for several years. Known limitations of testosterone immunoassays are the cross-reactivity with other steroids and a high variation in the low concentration range. We hypothesized that one of the additional limitations of testosterone immunoassays is an ineffective displacement of testosterone from its binding protein.Methods: Thirty samples from women not using oral contracepti...

In recent years measurement of steroid hormones like testosterone, androstenedione, cortisol, and cortisone has become increasingly important in both patient care and research. This is mainly due to the simple and non-invasive sample collection. We investigated in twenty healthy volunteers whether there is a difference between steroid hormone concentrations in unstimulated and parotid gland saliva as well as stimulated saliva collected while chewing without aid, using cotton a...

1,25-dihydroxyvitamin D3, the hormonally active metabolite of vitamin D3, tightly controls calcium blood levels. An increase of 1,25-dihydroxyvitamin D3 leads to an increase in calcium concentration with calcium originating from various resources, including bone tissue. To assess a patient’s vitamin D status the precursor metabolite 25-hydroxyvitamin D3 is determined. However, measurement of 1,25-dihydroxyvitamin D is required w...

The adrenal and gonadal androgens testosterone, androstenedione and dehydroepiandrosterone (DHEA) play an important role in sexual development and fertility as well as in several other processes. We developed a method to assess serum testosterone, androstenedione and DHEA levels in one run using isotope-dilution liquid-chromatography tandem mass spectrometry (ID-LC-MS/MS). Sample preparation consisted of addition of internal standards (13C3-testosterone, ...

Recently, liquid chromatography–tandem mass spectrometry (LC–MS/MS) was stated to be the method of choice to measure sex steroids.1 Information on the mutual agreement of LC–MS/MS methods, however, is scarce. Therefore, we compared seven published LC–MS/MS methods for the simultaneous measurement of testosterone, androstenedione, and DHEA. Fifty-five random serum samples obtained from volunteers were analysed in duplicate by seven published LC&#1...