Vitamin D levels and obstructive sleep apnoea in children.

Objective: Obstructive sleep apnoea (OSA) is a common health problem in children. African American (AA) and obese children have higher prevalence of OSA, and are also at a higher risk of reduced vitamin D levels. We hypothesised that OSA would be associated with lower levels of plasma 25-hydroxyvitamin D (25(OH)D) and increase in the risk of metabolic dysfunction and systemic inflammation.

Methods: In this observational cross-sectional study, 176 prospectively recruited children (mean age: 6.8±0.8 years) underwent overnight polysomnographic evaluation and a fasting blood draw the morning after the sleep study. In addition to lipid profile, homeostatic model of insulin resistance (HOMA-IR) and high-sensitivity C-reactive protein (hsCRP) assays and plasma 25(OH)D levels were assessed using ELISA kits.

Results: AA children, obese children and children with OSA had significantly lower 25(OH)D levels. Linear associations emerged between 25(OH)D plasma levels and body mass index (BMI) z-score, hsCRP and HOMA-IR, as well as with apnoea-hypopnoea index (AHI) and oxygen saturation (SpO2) nadir, the latter two associations remaining statistically significant even when controlling for all other potential confounders, and independently accounting for 17.7% of the variance in 25(OH)D (p<0.01).

Conclusions: 25(OH)D levels are reduced in paediatric OSA, in AA children and in obese children, particularly when all are present, and may play a role in modulating the degree of insulin resistance and systemic inflammation. The short-term and long-term significance of reduced 25(OH)D in paediatric OSA remains undefined.