Vitamin D is a steroid hormone classically involved in the calcium metabolism and bone homeostasis. Recently, new and interesting aspects of vitamin D metabolism has been elucidated, namely the special role of the skin, the metabolic control of liver hydroxylase CYP2R1, the specificity of 1α-hydroxylase in different tissues and cell types and the genomic, non-genomic and epigenomic effects of vitamin D receptor, which will be addressed in the present review. Moreover, in the last decades, several extraskeletal effects which can be attributed to vitamin D have been shown. These beneficial effects will be here summarized, focusing on the immune system and cardiovascular system.

PARAT, a new European Society of Endocrinology program, aims to identify unmet scientific and educational needs of parathyroid disorders, such as primary hyperparathyroidism (PHPT), including parathyroid cancer (PC), and hypoparathyroidism (HypoPT). The discussions and consensus statements from the first PARAT workshop (September 2018) are reviewed. PHPT has a high prevalence in Western communities, PHPT has a high prevalence in Western communities, yet evidence is sparse concerning the natural history and whether morbidity and long-term outcomes are related to hypercalcemia or plasma PTH concentrations, or both. Cardiovascular mortality and prevalence of low energy fractures are increased, whereas Quality of Life is decreased, although their reversibility by treatment of PHPT has not been convincingly demonstrated. PC is a rare cause of PHPT, with an increasing incidence, and international collaborative studies are required to advance knowledge of the genetic mechanisms, biomarkers for disease activity, and optimal treatments. For example, ~20% of PCs demonstrate high mutational burden, and identifying targetable DNA variations, gene amplifications and gene fusions may facilitate personalized care, such as different forms of immunotherapy or targeted therapy. HypoPT, a designated orphan disease, is associated with a high risk of symptoms and complications. Most cases are secondary to neck surgery. However, there is a need to better understand the relation between disease biomarkers and intellectual function, and to establish the role of PTH in target tissues, as these may facilitate the appropriate use of PTH substitution therapy. Management of parathyroid disorders is challenging, and PARAT has highlighted the need for international transdisciplinary scientific and educational studies in advancing in this field.

This review explores the dual role of skeletal muscle as both a mechanical and endocrine organ, highlighting its contributions to overall health and its adaptability to various inputs such as nutrition, hormones, exercise, and injuries. In addition to its role in metabolism and energy conversion, skeletal muscle secretes signalling molecules called myokines (at rest) and exerkines (during/after physical exercise), which communicate with other organs like the brain, the cardiovascular system, and the immune system. Key molecules such as interleukins, irisin, and myostatin are discussed for their roles in mediating muscle health and inter-organ communication. This work also focuses on the muscle–gut axis, emphasising the bidirectional interaction between skeletal muscle and the gut microbiota, a complex ecosystem influencing immune defence, digestion, and metabolism. Muscle activity, particularly exercise, alters the gut microbial composition, promoting beneficial species, while gut-derived metabolites like short-chain fatty acids (SCFAs) impact muscle metabolism, mitochondrial function, and insulin sensitivity. Dysbiosis, or an imbalanced microbiota, can lead to muscle atrophy, inflammation, and metabolic dysfunction. This evidence highlights emerging research into myokines and exerkines as potential therapeutic targets for managing conditions like muscle decline, ageing, and metabolic diseases through muscle–gut interactions.