Daytime decrease of prolactin levels is associated with PCOS regardless to nutritional status and other hormones levels.

OBJECTIVE: The aim of the study is to analyze daytime changes of prolactin level depending on nutritional status and polycystic ovary syndrome (PCOS).

STUDY DESIGN: One hundred and fifteen (69 normal weight, 21 overweight and 25 obese) diagnosed with PCOS and 77 (37 normal weight, 18 overweight and 22 obese) women - Non-PCOS without concomitant diseases were enrolled. Body mass and height were measured and BMI was calculated. Serum concentrations of FSH, LH, E2, testosterone, TSH and PRL were determined morning 6.00 a.m. after wake. Second measurement of PRL was performed at 4 p.m.

RESULTS: The daytime decrease of prolactin level was higher in PCOS than in Non-PCOS group regardless of nutritional status (normal weight 35.8 ± 26.0 vs. 24.3 ± 15.3 ng/mL; overweight 28.5 ± 25.4 vs. 17.5 ± 8.8 ng/mL and obese 23.2 ± 21.1 vs. 18.4 ± 11.6 ng/ml, respectively). However, in both PCOS and Non-PCOS daytime changes of prolactin level were higher in normal weight than overweight and obese women (35.8 ± 26.0 vs. 28.5 ± 25.4 vs. 23.2 ± 21.1 ng/mL and 24.3 ± 15.3 vs. 17.5 ± 8.8 vs. 18.4 ± 11.6 ng/mL, respectively). The multivariate regression analysis revealed that the daytime changes of prolactin level are proportional to TSH concentration and coexistence of PCOS as well as inversely relative to BMI.

CONCLUSIONS: In conclusions, our results suggest that overweight and obesity decreased morning PRL level and impaired its daytime decrease, but coexistence of PCOS enlarged its.