Assessment of vitamin D status in Czech children

Objective: Vitamin D deficiency is a global health problem. The aim of this study was to determine the proportion of Czech children with vitamin D deficiency and examine related factors. Methods: The study subjects were 419 healthy children aged 5 and 9 years. Severe vitamin D deficiency was defined as a serum 25(OH)D level of 75 nmol/L (34% of children). Results: Serum 25(OH)D levels varied mainly with season. The highest levels of 25(OH)D were reached in autumn (median: 79.0 nmol/L), followed by summer (median: 67.8 nmol/L) and winter (median: 56.0 nmol/L). The lowest median value (49.8 nmol/L) was detected in spring. Conclusion: Children with sufficiency 25(OH)D levels were more frequently exposed to the sun and exposed a larger part of their body to the sun while spending time outdoors. Levels of 25(OH)D were also associated with using vitamin D supplements within six weeks before sampling.