Vitamin D level in children between 6-24 months and parameters affecting use

Objective: Vitamin D is a steroid hormone that affects calcium-phosphorus metabolism in the body. The primary effect of this hormone, mainly on bone tissue, is disrupted bone mineralization in its deficiency. Clinically, vitamin D deficiency manifests as rickets in children and osteomalacia in adults. Moreover, in conditions of vitamin D deficiency, not only does mineralization in bone tissue deteriorate, but it can also affect the development of many diseases, including autoimmune diseases, diabetes, cardiovascular disorders, multiple sclerosis, rheumatoid arthritis, and cancer. The most well-known causes of vitamin D deficiency are insufficient sunlight exposure and inadequate intake of vitamin D through diet. The Endocrine Society recommends a daily intake of 400 IU of vitamin D for every infant from birth to 12 months. In Turkey, vitamin D prophylaxis is recommended to be regularly administered by the Ministry of Health up to 12 months of age. The aim of this study is to identify the parameters affecting vitamin D levels in children aged 6-24 months and to examine the factors influencing vitamin D usage. Matherials and Methods: The data was obtained through face-to-face interviews with the families of children aged 6-24 months who applied to the Department of Pediatrics at Ankara Bilkent City Hospital for any reason and had their 25-OHD levels measured between November 2023 and February 2024, a period of four months. The child's gender, age, mother's age, number of siblings, family type, income status, nutritional status, maternal use of vitamin D during pregnancy, child's vitamin D use, type of vitamin D preparation used, frequency, and regimen of vitamin D use were queried. Statistical analyses of the obtained data were conducted using the SPSS (IBM SPSS Statistics 27) package program. Results: It was found that the average age of the children included in the study was 13.48±4.78 months. The gender distribution showed that 52.8% were female and 47.2% were male. It was learned that 67% of the children regularly used vitamin D supplements, while 11.3% used them irregularly, and 21.7% did not use them at all. 68.9% of the patients were found to have normal 25-OHD levels. It was observed that 20.6% of the children had a deficiency and 10.5% had insufficiency of 25-OHD levels. viii Among the 267 children aged between 6-24 months who applied, 179 were actively using vitamin D supplements regularly (64%), 30 were using them irregularly (11%), and 58 (25%) were not actively using vitamin D supplements. It was found that the 25-OHD levels of those who used vitamin D supplements irregularly or not at all were significantly lower compared to those who used them regularly. It was observed that as the age of the patients increased, the use of vitamin D supplements decreased, and their 25-OHD levels decreased as well. Socioeconomic factors did not create a significant difference in 25-OHD levels. Positive correlations were found between the use of vitamin D during pregnancy and both the use of vitamin D supplements by children and their 25-OHD levels. Conclusion: Based on the analyses conducted in this study, it is recommended that vitamin D prophylaxis and treatment should be continued with appropriate dosing, especially after the age of 1 year. It is advised to ensure the continuity of vitamin D supplementation in patients consulting family physicians. It was observed that appropriate doses should be updated as age increases and vitamin D supplementation should be initiated as early as possible. Keywords: Vitamin D, Child, Prophylaxis, Calcium, Rickets