Endocrine Abstracts

Circulating estrogens decrease after the menopause from 60–400 to 5–30 pg/ml in postmenopausal women and in men are below 30 pg/ml. These low physiological concentrations present an analytical challenge. Analysis of steroids by tandem mass spectrometry is attractive due to its high specificity compared with immunoassays. However, estrogens do not ionise efficiently and therefore chemical modifications are necessary to achieve the sensitivity required.<p class="ab...

Liquid Chromatography tandem mass spectrometry (LC–MS/MS) is gold-standard for androgen analysis in biological fluids, superseding immunoassays in specificity, particularly at low concentrations. While LC–MS/MS is well established for analysis of testosterone (T) and androstenedione (A4), 5α-dihydrotestosterone (DHT) presents greater analytical challenges. DHT circulates at low nanomolar concentrations in men and lower in women, ionising inefficiently. Thus, eve...

Excess action of glucocorticoid hormones is implicated in metabolic disease and cognitive decline, 11β-hydroxysteroid dehydrogenase 1 (11βHSD1) catalysing generation of active glucocorticoid hormones in tissues. The penetration rates and tissue-specific contribution of 11βHSD1 to glucocorticoid turnover were assessed using tracer kinetics. 9,11,12,12-d4-Cortisol (d4F) was infused (1.75 mg/day, 7 days) into C57Bl6/J male mice and mice lacking 11βHSD1 (n<...

Physiological circulating concentrations of estrogens are very low in men and postmenopausal women (<50 pg/ml), which presenting analytical challenges. Immunoassays can detect as low as 30 pg/ml, but cross-reactivity is a concern. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) offers greater specificity than immunoassays, but ionisation of estrogens is inefficient. Derivatisation, which introduces charged moieties, may enhance ionisation. Dansylated de...