Association of vitamin D status with COVID‐19 disease severity in pediatric patients: A retrospective observational study

BACKGROUND AND AIMS: Vitamin D deficiency is associated with increased vulnerability to respiratory infections. This study aimed to determine the potential relationships between coronavirus disease 2019 (COVID‐19) severity, serum vitamin D concentrations, and some inflammatory markers among pediatric COVID‐19 patients in Iran. METHODS: A retrospective study was conducted among hospitalized pediatric COVID‐19 cases in Abuzar Hospital (Ahvaz, Iran) for 6 months. The COVID‐19 diagnosis was based on the real‐time reverse transcription‐polymerase chain reaction technique. Demographic and clinical data of patients were recorded. Patients with serum vitamin D levels lower than 20 ng/ml were assigned as Group 1 and those with serum vitamin D concentrations equal to or more than 20 ng/ml were considered as Group 2. RESULTS: A total of 144 patients were enrolled. Their mean age was 80 ± 49 months (range: 1–16 years). Patients in Group 1 had significantly lower levels of serum vitamin D, calcium, and lymphocytes, as well as higher fibrinogen, d‐dimer, and C‐reactive protein (CRP) levels compared with those in Group 2 (p < 0.001). In addition, they had a significantly higher dry cough, fever, chest radiographic findings, respiratory rate, and longer hospital length of stay than patients in Group 2. Serum concentrations of vitamin D were positively correlated with levels of serum calcium, lymphocytes, and neutrophils but negatively correlated with CRP, fibrinogen, and d‐dimer values. Furthermore, patients with moderate or severe courses of COVID‐19 had significantly higher inflammatory markers (CRP, d‐dimer, and fibrinogen), as well as lower levels of serum calcium, vitamin D, lymphocytes, and neutrophils than those with mild COVID‐19 (p < 0.001). In the multivariate analysis, fibrinogen level on admission was detected as the independent predictor of severe COVD‐19 (odds ratio = 1.06, 95% confidence interval: 1.03–1.09; p < 0.001). CONCLUSION: This study indicated associations between the severity of COVID‐19, serum vitamin D concentrations, and some inflammatory markers in pediatric COVID‐19 patients.