Endocrine Abstracts

Introduction: The measurement of male androgens in most NHS laboratories is often limited to testosterone alone. To more accurately determine the androgen status in men the measurement of other androgens such as DHT and DHEA would be beneficial however these are difficult to measure without derivatisation. We report a combined LC–MS/MS assay for the measurement of testosterone, androstenendione, DHT and DHEA on a small sample volume.Methods: Zinc su...

Introduction: Most clinical laboratories use immunoassays to measure estradiol despite limitations such as poor specificity, poor sensitivity and wide variability between different manufacturers’ assays. LC–MS/MS assays overcome the issues of sensitivity and specificity however the methods reported in the literature often involve complex sample preparation and lengthy run times. We describe a simple, rapid assay for the simultaneous measurement of serum estradiol and...

Introduction: Testosterone measurement by liquid chromatography tandem mass spectrometry (LC-MS/MS) is well accepted as the preferred technique for the analysis of serum testosterone in both males and particularly females. However variation is seen between LC-MS/MS assays and is most likely to be due to method differences between laboratories. One area of inconsistency amongst routine LC-MS/MS assays is the choice of internal standard. We investigated the effects of three inte...

Introduction: Prednisolone is well known to interfere in routine immunoassays for cortisol with uncertainty surrounding the degree of this interference. Methods using tandem mass spectrometry technologies offer more specificity, however there have been some reports of prednisolone interference in mass spectrometry assays. We aimed to characterise the extent of prednisolone interference in both an automated immunoassay and a tandem mass spectrometry method (TMS).<p class="a...

Introduction: Methodological differences in the immunoassay measurement of cortisol are apparent when reviewing External Quality Assessment scheme data. A bimodal distribution is often observed, particularly for samples from female subjects. It has been postulated that some immunoassays are inefficient at removing cortisol from its binding proteins and therefore have the potential to under-recover from female samples. We investigated the results obtained from two immunoassays ...

Introduction: There has been much interest recently in measuring both salivary cortisol and cortisone due to the presence of 11β-hydroxysteroid dehydrogenase type 2 enzyme in the salivary glands. This enzyme facilitates the conversion of cortisol to cortisone; hence the concentration of cortisone in saliva may also be of interest. Studies have shown recently that salivary cortisone and cortisol are good markers of serum free cortisol status.Methods:...

The measurement of plasma renin activity is required in a number of clinical situations, in particular screening for primary aldosteronism (PA) and monitoring mineralocorticoid replacement therapy. PA is a treatable cause of hypertension and has an estimated prevalence of up to 20% amongst resistant hypertensives. Consequently, recent guidelines now recommend screening for PA in all patients groups with a high prevalence of PA. At present, the most reliable method of screening...

Introduction: It has been recognised in EQA schemes in Europe and America that the reproducibility between labs using LC–MS for testosterone analysis is not optimal for this technique. We decided to conduct a calibration exercise to investigate the variability seen between labs.Methods: Aqueous and matrix matched serum samples were sent to labs participating in the NEQAS testosterone scheme. The labs were asked to measure these samples blind using t...

Saliva contains the free unbound fraction of testosterone, which has been shown to correlate with the free circulating serum testosterone, and may better reflect the physiologically active form. Recently, measurement of free testosterone has gained international recommendations for the diagnosis of hypogonadism in the ageing male. Saliva collection is a non-invasive technique, offering more flexibility to the patient, e.g. the collection of samples at home. Liquid chromatograp...

Traditionally, oestradiol measurement is performed by immunoassay. The sensitivity of these assays is not sufficiently sensitive for certain patient groups such as males, post-menopausal females and children. There is also a potential for interference from structurally related compounds or heterophilic antibodies. LC–MS/MS is an attractive alternative as it has increased sensitivity and specificity.We reviewed the requests for LC–MS/MS analysis...