Insulin and body weight but not hyperandrogenism seem involved in seasonal serum 25-OH-vitamin D3 levels in subjects affected by PCOS

PCOS patients were frequently characterized by lower plasma vitamin D levels. The mechanisms involved in this dysfunction remains still debated, therefore we evaluated the role of androgen, insulin and body weight on the serum VitD levels in women with or without PCOS. Eighty one patients 18–42 yrs old were studied into “SUMMER” and “WINTER” seasonal period: thirty seven PCOS, seventeen no-ovarian hyperandrogenic (noPCOS), twelve functional hypothalamic amenorrhea (FHA) and finally fifteen healthy (Con). Patients were further divided into: lean (L), obese (O), normo- (nINS) and hyperinsulinemic (hINS). All hormonal and metabolic parameters were measured at 1-7 days of the menstrual cycle. Our results show that VitD levels were lower in PCOS and in noPCOS than in FHA and Con, in particular in (O) and (hINS) PCOSs. Both in summer and in winter, PCOSs had basal VitD levels significantly lower than FHA and Con, whereas they were similar to noPCOS. Yet, LhINS and OPCOS had VitD levels lower than Con and noPCOS. VitD levels were comparable in LnINS PCOS and Con. In conclusion, PCOSs had levels of VitD lower than controls. Weight and hyperinsulinemia had a significant influence on these values. Finally, over 70% of our healthy patients had VitD deficiency.