RT Journal Article T1 Vitamin D Endocrine System and COVID-19 A1 Bouillon, Roger A1 Quesada-Gomez, José Manuel K1 Vitamin D K1 Calcifediol K1 COVID-19 K1 Mortality K1 Acute respiratory distress syndrome K1 Intensive care treatment K1 Vitamina D K1 Mortalidad K1 Síndrome de dificultad respiratoria AB Preclinical data strongly suggest that the vitamin D endocrine system (VDES) may have extraskeletal effects. Cells of the immune and cardiovascular systems and lungs can express the vitamin D receptor, and overall these cells respond in a coherent fashion when exposed to 1,25-dihydroxyvitamin D, the main metabolite of the VDES. Supplementation of vitamin D-deficient subjects may decrease the risk of upper respiratory infections. The VDES also has broad anti-inflammatory and anti-thrombotic effects, and other mechanisms argue for a potential beneficial effect of a good vitamin D status on acute respiratory distress syndrome, a major complication of this SARS-2/COVID-19 infection. Activation of the VDES may thus have beneficial effects on the severity of COVID-19. Meta-analysis of observational data show that a better vitamin D status decreased the requirement of intensive care treatment or decreased mortality. A pilot study in Cordoba indicated that admission to intensive care was drastically reduced by administration of a high dose of calcifediol early after hospital admission for COVID-19. A large observational study in Barcelona confirmed that such therapy significantly decreased the odds ratio (OR) of mortality (OR = 0.52). This was also the conclusion of a retrospective study in five hospitals of Southern Spain. A retrospective study on all Andalusian patients hospitalized because of COVID-19, based on real-world data from the health care system, concluded that prescription of calcifediol (hazard ratio [HR] = 0.67) or vitamin D (HR = 0.75), 15 days before hospital admission decreased mortality within the first month. In conclusion, a good vitamin D status may have beneficial effects on the course of COVID-19. This needs to be confirmed by large, randomized trials, but in the meantime, we recommend (rapid) correction of 25 hydroxyvitamin D (25OHD) deficiency in subjects exposed to this coronavirus. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. PB Wiley-Blackwell Publishing YR 2021 FD 2021-12 LK http://hdl.handle.net/10668/3660 UL http://hdl.handle.net/10668/3660 LA en NO Bouillon R, Quesada-Gomez JM. Vitamin D Endocrine System and COVID-19. JBMR Plus. 2021 Nov 17;5(12):e10576. DS RISalud RD Apr 11, 2025