Hypovitaminosis D and the endocrine phenotype of COVID-19

Background: Vitamin D and its deficiency have recently been suspected to be involved in increased susceptibility and negative outcomes of COVID-19. This assumption was based on the well known immunomodulatory actions of vitamin D and on the consistent finding of low levels of 25 hydroxyvitamin D (25OHD) in hospitalized patients with COVID-19. Moreover, several studies reported a correlation between 25OHD levels and different clinical outcomes of the disease. Aim: Aim of the current review was to approach the topic of vitamin D and COVID-19 from a different perspective summarizing the data which led to the evidence of the existence of an endocrine phenotype of COVID-19. Conclusions: This review analyzed in the light of the current knowledge the possibility that several endocrine manifestations of COVID-19 could be holistically interpreted in the context of an inadequate vitamin D status.