Hypovitaminosis D and the endocrine phenotype of COVID-19

Abstract

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. Keywords Vitamin D • Hypocalcemia • Vertebral fractures • Diabetes mellitus • Obesity • COVID-19

COVID-19 and the pituitary

“…SIADH was found in about 40-50% of patients with hyponatremia in the pre-pandemic era, thus representing the most recognizable cause of this electrolyte disorder; the prevalence was even higher in some pathological conditions such as atypical pneumonia and hyper-inflammation syndrome [78], among main complications of SARS-CoV2 infection [79]. Therefore, it seems reasonable to think that the prevalence of SIADH may be high even in COVID-19 patients.…”

The emerging osteo-metabolic phenotype of COVID-19: clinical and pathophysiological aspects

“…At the beginning of the COVID-19 spread in Europe, vitamin D deficiency was hypothesized to have a role in increased SARS-CoV-2 infection susceptibility and negative outcomes of COVID-19 (ref. 3 ). In fact, vitamin D is well known to be crucial for skeletal homeostasis, but it also has many extra-skeletal systemic functions, including immunomodulation and immunocompetence in innate and adaptive immunity 8 .…”

“…Furthermore, vitamin D deficiency is also very frequent in patients with type 2 diabetes mellitus and obesity who are known to be at increased risk of severe COVID-19 (ref. 3 ).…”

“…In patients with obesity, low levels of vitamin D are inversely related to BMI and adiposity, negatively influencing skeletal and muscle health with a resulting increased predisposition to an obese osteo-sarcopenic phenotype 3 . As vitamin D can also have a protective effect on β-cells and might modulate adipose tissue distribution 3 , it can be hypothesized that a bidirectional relationship exists between diabetes mellitus, altered body composition and reduced vitamin D levels. This relationship might have clinical implications in patients with COVID-19, increasing their risk of poor outcomes 3 .…”

“…As vitamin D can also have a protective effect on β-cells and might modulate adipose tissue distribution 3 , it can be hypothesized that a bidirectional relationship exists between diabetes mellitus, altered body composition and reduced vitamin D levels. This relationship might have clinical implications in patients with COVID-19, increasing their risk of poor outcomes 3 .…”