Serum melatonin in women with polycystic ovary syndrome

There has been a surge of interest in recent years in studying the changes of serum melatonin concentrations in disorders that are associated with insulin resistance such as diabetes mellitus type 2 and polycystic ovary syndrome (PCOS).

The present study was designed to investigate the day-time and night-time levels of serum melatonin and the cortisol rhythm in women with PCOS and compare them with those of healthy women.

This is a case-control study which included 30 women with PCOS and 25 healthy women. All hormonal measurements in both the study group and controls were carried out between days 3 and 5 counted from the beginning of the last regular menstrual cycle; they included serum levels of melatonin and cortisol at 03:00 a.m and 08:00 a.m, total testosterone (T), dehydroepiandrosterone sulfate (DHEA-S), luteinizing hormone (LH), follicle stimulating hormone (FSH), and immunoreactive insulin at 08:00 a.m.

Women with PCOS were found to have a significantly higher melatonin level at 08:00 a.m. and smaller mean night-day difference in the concentrations of melatonin in comparison with those of healthy women (natural log (Ln) night-day difference 0.60 +/- 0.10 pg/ml versus 1.15 +/- 0.14, p < 0.002). Melatonin to cortisol ratios at 03:00 a.m. and 08:00 a.m. showed no statistically significant differences between the two groups (Ln melatonin/cortisol 03:00 a.m., 1.01 +/- 0.06 versus 1.05 +/- 0.05; Ln melatonin/cortisol at 08:00 a.m., 0.62 +/- 0.01 versus 0.56 +/- 0.03, p > 0.05).

The results we obtained about the changes of melatonin in women with PCOS could help in elucidating the complex pathophysiological pattern of this disease.