Thakur P, Potluri P., et al. - In populations residing at high altitudes, this study was undertaken to investigate the relationship of serum vitamin D levels with chronic rhinosinusitis (CRS) and to assess its correlation with the CRS severity. Researchers performed a prospective case-control study comparing vitamin D in 60 patients (30 with nasal polyposis and 30 without) and 31 controls. Using Spearman’s correlation, the relationship between vitamin D and the severity of disease (Lund Mackay CT/LMS and endoscopic Lund Kennedy scores/LKS) was evaluated. In adults residing at high altitudes, a significantly lower vitamin D level is correlated with CRS, regardless of the presence or absence of nasal polyposis. For CRS, vitamin D is an independent predictive factor. Between CRS with vitamin D, the study found an inverse moderate correlation of severity.