Melatonin and its correlation with testosterone in polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is considered to be the most common endocrine disorder affecting women. Melatonin, a small lipophilic indoleamine, and reproductive hormones may be interrelated. Melatonin influences sex steroid production at different stages of ovarian follicular maturation as melatonin receptors have been demonstrated at multiple sites in ovary and in intrafollicular fluid. It plays role as an antioxidant and free radical scavanger which protects follicles from oxidative stress, rescuing them from atresia, leading to complete follicular maturation and ovulation.

To study the role of melatonin in PCOS and to investigate its correlation with testosterone in patients suffering from PCOS.

A total of 50 women with PCOS (Rotterdam criteria, 2003) and 50 age and weight matched healthy controls were selected and serum melatonin estimation was done in both the groups and correlated with serum total testosterone levels.

In a case-control study, detailed history, clinical examination and hormonal evaluation [basal levels of leutinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, prolactin, insulin, total testosterone, progesterone and melatonin] were carried out in all the participants including both cases and controls. For melatonin estimation, blood samples were collected between 12:00 am and 04:00 am on day 2(nd) of menstrual cycle and analyzed by using commercially available enzyme-linked immunosorbent assay kit.

Student's t-test was used to compare the significant difference in mean values between cases and control groups. Chi-square test was used to test the significant association between the qualitative variables. Linear correlation coefficient and regression analysis were done to see the amount and direction of relationship between quantitative variables.

The mean melatonin level was observed to be significantly increased in patients (63.27 ± 10.97 pg/mL) than in controls (32.51 ± 7.55 pg/mL). Melatonin was found to be raised in all the cases of PCOS (above cut-off value of ≥45 pg/mL, P < 0.001). Total testosterone level was also raised in 72% of patients. Melatonin levels were found to be positively associated with increased testosterone (P < 0.001). In regression analysis using melatonin as dependent variable and testosterone as an independent variable, the value of R2 Χ 100 (percent variation) was found to be 72.1%.

Women with PCOS have significantly raised serum melatonin levels and hyperandrogenemia along with increased number of atretic follicles. Further studies are required to establish a definite role of melatonin in PCOS cases with disturbed hormonal milieu. This could open up the way for therapeutic role of melatonin in treatment of patients suffering from PCOS.