Melatonin circadian rhythm in women with idiopathic hyperprolactinemia.

Objectives: Relationship between melatonin and prolactin has been suggested on the basis of both experimental and clinical studies. However, there are scarce and controversial data concerning melatonin concentrations in hyperprolactinemic patients. Therefore, the aim of the present study was to evaluate the circadian rhythm of melatonin in female patients suffering from hyperprolactinemia.
Material and Methods: The study was performed on 28 women aged 17-58 years (mean+/-SEM: 30.5+/-1.8 years) suffering from idiopathic hyperprolactinemia and 14 healthy volunteers aged 20-50 years (mean+/-SEM: 36.4+/-3.0 years) with normal prolactin levels. Blood samples for measurements of serum melatonin and prolactin concentrations were collected at 08:00, 12:00, 16:00, 20:00, 24:00, 02:00, 04:00, 06:00, and 08:00 h. Melatonin and prolactin concentrations were measured by enzyme immunoassay.
Results: Significant increase in melatonin serum concentrations was also observed in hyperprolactinemic patients in comparison with healthy volunteers during the night. Similar increase was also observed in the area under curve of melatonin concentrations. However, no correlation was found between prolactin and melatonin concentrations in any examined time points.
Conclusion: The results of the present study confirm suggestions of the presence of the relationship between melatonin and prolactin secretion.