Endocrine Abstracts

Almost all hormonal systems are dynamic with hormones being secreted in various combinations of ultradian, circadian, monthly and even yearly patterns.These patterns have emerged as natural consequences of the multilevel regulation of the hormone axes themselves and in response to environmental conditions such as the light:dark cycle, food availability and temperature. The Hypothalamic-Pituitary-Adrenal (HPA) axis is critical for life and delivers a complex system of pulsed steroid release from the adrenal gland with an approximate hourly ultradian rhythm underlying a much better recognised circadian rhythm. Both of these rhythms have been shown to be critical for good health, and are an important aspect of the regulation of cognitive, appetitive,metabolic, immunological and cardiovascular function. Since these oscillating levels of corticosteroids are so important for health, and so many disease processes from Cushings disease, hyperaldosteronism and Addisons disease to metabolic immunological and psychiatric disorders., are associated with HPA dysfunction, it is clearly important to be able to assess 24 hour hormone levels. As it is not feasible to take multiple blood samples from subjects going about their normal lives- including during normal sleep- we have designed a novel automated ambulatory sampling system that allows us to sample interstitial fluid hormone levels in normal ambulant subjects (www.u-rhythm.co.uk). Using our automated sampler the Horizon 2020 funded ‘Ultradian’ project between Bergen, The Karolinska, Athens and Bristol, has now published our first paper on 214 normal subjects to establish normal indices for the dynamic changes in the corticosteroidome across the day. I will be discussing the rich data set from these subjects and what it tells us about the heterogeneity of HPA activity between normal subjects, differences between blood and tissue for cortisol and cortisone levels,and the remarkable evidence for differences in aldosterone regulation between different subjects.The use of multiple sampling technology for the diagnosis and management of patients with adrenal disorders will be discussed by Dr Thomas Upton in his talk on Monday.