Endocrine Abstracts

Background: Significant changes in calcium metabolism occur during normal pregnancy to meet the needs of the growing fetus. These include a rise in 1,25-dihydroxyvitamin D (1,25-(OH)D2 and consequent suppression of parathyroid hormone (PTH). In spite of this, maternal hypercalcaemia is very uncommon and should prompt further investigation.Clinical case: A 24-year-old primigravida woman was referred for assessment of maternal hypercalcaemia. Sh...

Control mechanisms of adrenocorticotrophic hormone (ACTH) and cortisol (CORT) secretion and metabolism during acute systemic inflammation (e.g. major surgery) have never been clearly elucidated. We sampled blood every 10 minutes for 12 h during and after coronary artery bypass grafting (CABG) in 10 patients to create profiles of ACTH, CORT and inflammatory mediators and compared these to healthy controls. Patients’ ACTH and CORT responses were classified into one of three...

Background: Hormones oscillate in circadian and ultradian rhythms. Consequently, single time point measurements are very difficult to interpret. To address this, we developed an automated system of 24-hour ambulatory microdialysis. This allows measurement of free hormone concentrations in subcutaneous interstitial fluid collected while participants continue normal daily activities. To validate the technique for adrenal steroid hormones, we simultaneously sampled interstitial f...

Pituitary and adrenal gland assessment, is one of the most important aspects of the management of a pituitary and adrenal adenoma.Clinical practice varies widely with regard to assessment of pituitary and adrenal status pre- and post-operative. Pre-operative testing includes dynamic testing to assess function which is not practical in the immediate post-operative period. Instead a single morning serum total hormones are measured while a more definitive a...

Background: Hormones oscillate in circadian and ultradian rhythms. Single time point samples are difficult to interpret and high frequency measurements are time consuming, expensive and invasive. We developed a minimally invasive technique of ambulatory, automated microdialysis. This allows frequent 24-hour sampling of interstitial fluid while participants continue normal daily activities.Methods: Healthy volunteers (age 18–68, no regular medication...

Rhythms and change are fundamental properties of all living things, having evolved to allow adaptation to life on earth. Rhythmicity can be observed both in behaviour and internal biology of all mammals including humans. Hormonal secretion patterns that occur at circadian and or ultradian frequencies occur commonly in the endocrine system but for practical and pragmatic reasons clinicians tend to sample and attempt to interpret single time point measures. These results can oft...

Background: Establishing endocrine diagnoses including pituitary Cushing’s remains challenging with delayed or misdiagnosis being very costly for both patient and the health care system. A key issue is that standard diagnostic tests are typically single time point, single analyte samples, which do not consider dynamic variation intrinsic to endocrine systems. Having previously demonstrated that free tissue hormones correlate strongly with plasma concentrations, we present...

Patients on long term glucocorticoid replacement therapy have higher rates of morbidity and mortality. One causative factor may be non-physiological cortisol replacement. We have developed as part of the ULTRADIAN consortium (https://www.uib.no/en/ultradian) the U-RHYTHM, an ambulatory bio-sampling device that can collect clinical samples using in-vivo microdialysis every 20 minutes over the 24hour day whilst individuals continue with their normal everyday activities....

Adrenal hormones possess both circadian and ultradian rhythms, making interpretation of single time point measurements difficult, particularly in the context of suspected endocrine disease. Attempting to capture either normal or pathological rhythms in detail by traditional measurement of blood is impractical and generally unfeasible. However, minimally invasive microdialysis sampling of free tissue hormones coupled with a portable fraction collector (U-RHYTHM), and a targeted...