Endocrine Abstracts

Low vitamin D levels were consistently reported as a risk factor for worse outcomes in hospitalized COVID-19 patients. Emerging evidences suggest that in 50–70% of COVID-19 survivors several post-COVID symptoms can be observed up to 3 months after acute-disease, representing a novel clinical condition defined Long-COVID syndrome. To date, the predisposing factors for this syndrome are still poorly understood. We retrospectively aimed at evaluating the influence of 25(OH) vitamin D levels on Long-COVID occurrence in patients previously hospitalized for COVID-19, re-assessed 6-months after discharge. Long-COVID was defined based on the National Institute for Health and Care Excellence-guidelines and approximately 500 patients were re-evaluated after the first pandemic-wave. While excluding patients with therapies/comorbidities affecting bone metabolism, and/or those admitted in ICU during hospitalization, only 50 Long-COVID patients were eligible for enrolment and compared in an age, sex, comorbidities and acute-disease characteristics-matched 1:1 ratio with non-Long-COVID patients. 25(OH) vitamin D was measured at hospital-admission and after 6-months. Median 25(OH) vitamin D levels were 14.7 and 20.6 ng/ml, at hospital-admission and at 6-month follow-up, respectively. At admission, vitamin D deficiency (25(OH) vitamin D <20 ng/ml) was found in 71 patients, and, at 6-month follow-up, in 46 patients. We observed lower 25(OH) vitamin D levels, evaluated at follow-up visit, in Long-COVID group than those without (20.1 vs 23.2 ng/ml, P=0.03). No statistically significant differences were observed regarding prevalence of vitamin D deficiency between those with and without Long-COVID. Regarding the different affected health areas evaluated in the entire cohort, we observed lower 25(OH) vitamin D levels in those with neurocognitive symptoms at 6-month visit (n.7) as compared to those without (n.93) (14.6 vs 20.6 ng/ml, P=0.042). In patients presenting vitamin D deficiency both at admission and at follow-up (n.42), those affected by Long-COVID (n.22) were characterized by lower 25(OH) vitamin D levels, evaluated at follow-up, compared to those not affected (n.20) (12.7 vs 15.2 ng/ml, P=0.041). In multiple regression analyses, lower 25(OH) vitamin D levels, evaluated at follow-up, resulted as the only variable significantly associated with the Long-COVID occurrence (P=0.016, OR 1.08-CI 1.01-1.15). In conclusion, COVID-19 survivors with Long-COVID have lower 25(OH) vitamin D levels as compared to matched patients without Long-COVID. Moreover, lower vitamin D resulted as an independent risk factor for the occurrence of this syndrome. Our data suggest that evaluating vitamin D levels in COVID-19 patients after hospital discharge and improving their vitamin D status when needed may be helpful in reducing the burden of COVID-19 sequelae.