Low testosterone levels and unimpaired melatonin secretion in young males with metabolic syndrome.

The interrelations between testosterone, insulin and melatonin levels in males with metabolic syndrome (MS) are still not clarified, especially in young age groups. The aim of the present study was to compare the testosterone serum levels in young men with MS to those in healthy controls, and to determine the possible changes in their melatonin rhythm, as well as the relation between melatonin, insulin and lipid profile. Fasting insulin and testosterone concentrations were measured in 10 healthy nonobese and 10 MS patients. Blood samples for melatonin, insulin and luteinizing hormone (LH) were collected at 19.00, 03.00 and 11.00 hours. A significant difference was found between the testosterone levels in controls and patients. Luteinizing hormone levels in both groups were similar, however, higher night LH levels in MS patients were observed. No changes in the melatonin concentrations of the two groups were found. In conclusion, total testosterone levels were significantly lower in young men with MS compared with healthy age-matched controls. Mild hypoandrogenia in hyperinsulinaemic patients was not related with changes in their melatonin levels. No alterations in the endogenous melatonin rhythm of the MS patients were found.