Multicentric Italian case-control study on 25OH vitamin D levels in children and adolescents with Prader-Willi syndrome

Purpose: 25OHD levels in patients with Prader-Willi Syndrome (PWS), the most frequent cause of genetic obesity with a peculiar fat mass distribution, are still debated. Insulin resistance (IR), Body Mass Index-SDS (BMI-SDS), Growth Hormone Therapy (GHT), and puberty onset seem to interact with 25OHD levels. The objectives of the study are: (1) To analyze 25OHD levels in pediatric PWS patients in comparison with a control group (CNT) (2) To evaluate a possible correlation between BMI-SDS, HOMA-IR, puberty, GHT, and 25OHD levels. Methods: This is a retrospective case–control, multicenter study. Data were collected among 8 different Italian Hospitals (outpatient clinics), over a period of four years (2016–2020). We included 192 genetically confirmed PWS and 192 CNT patients, aged 3–18 years, matched 1:1 for age, gender, BMI-SDS, Tanner stage, sun exposure, and month of recruitment. Results: No statistically significant differences in 25OHD levels were observed between the PWS population and the CNT (PWS 24.0 ng/mL vs CNT 22.5 ng/mL, p > 0.05), OR = 0.89 (95% CI 0.58–1.35). We observed a slight, although non-significant, reduction in 25OHD levels comparing NW and OB populations. HOMA-IR, puberty onset, genotype and GHT (previous or ongoing) did not show statistically significant correlation with 25OHD levels. Conclusions: Our findings could be useful for clinicians to optimize the therapeutic management as well as to increase awareness of PWS.