Seasonal variation and Vitamin-D status in ostensibly healthy Indian population: An experience from a tertiary care institute

Background: 25-hydroxy vitamin-D (25(OH)D) deficiency is prevalent worldwide including India. Earlier some cross-sectional studies have discussed 25(OH)D deficiency and its prevalence. The correlation of 25(OH)D with seasonal variation has been reported rarely in India. To determine the 25(OH)D levels and seasonal changes of 25 (OH)D status at a tertiary care hospital in North-western India. Materials and methods: 25(OH)D assessments performed in laboratories between 2018 and 2020 was acquired using hospital records. A total of 11,428 assays of serum 25(OH)D were analyzed in the study. Subjects were divided into three groups based on the International Endocrine Society's recommendation for serum 25(OH)D level. The 25(OH)D deficiency <20 ng/ml, insufficiency 20-29 ng/mL and sufficiency >= 30 ng/mL was defined. The months have been separated into the following seasons to analyze seasonal trends: Summer/monsoon (April-September), and winter/spring (October-March). Results: The median 25(OH)D was 17.2 ng/mL. We observed the prevalence of 60 %, 24.1 % & 15.9 % of 25(OH) D deficiency, 25(OH)D insufficiency, and sufficiency respectively in the total number of individuals tested. 56 % male and 63 % females were 25(OH)D deficient. Notably, the lowest median 25(OH)D value was found in the 21-30 age group (14.8 ng/mL). A significant difference in 25(OH)D levels between the summer (18.7 ng/mL) and winter (15.8 ng/mL) seasons has been noticed. Discussion: Current study revealing that 25(OH)D deficiency is common in all age groups and genders, according to our findings. Surprisingly, the lowest levels were reported in young adults. Seasonal variation has an impact on 25(OH)D status, however in all seasons 25(OH)D levels are lower than reference intervals. These findings suggest that the criteria for determining the state of 25(OH)D insufficiency and deficiency in the Indian population should be reconsidered.