Evaluation of serum prolactin levels in patients with endometriosis and infertility

The aim of this study was to clarify the significance of serum prolactin concentrations in patients with infertility and endometriosis. Forty patients with infertility and laparoscopically proven endometriosis were recruited into the study. Basal serum prolactin levels and prolactin levels after TRH administration were measured. The mean basal serum prolactin concentrations were 12.5, 16.5, 19.5, and 26.5 ng/ml and those after thyrotropin-releasing hormone (TRH) administration were 88.3, 114.2, 125.3 and 138.8 ng/ml in patients with stages I, II, III and IV endometriosis, respectively. A statistically significant relationship was found between the basal serum prolactin levels as well as those after TRH injection and the stage of the endometriosis. The patients were divided in two groups. Group I consisted of 20 patients who did not receive any treatment, while group II consisted of 20 patients who were initially treated with GnRH analogues for 24 week and subsequently with several therapeutic schemes in order to improve their fecundity. The pregnancy rate was not different between the two groups. The patients, however, who did not become pregnant had higher serum prolactin concentrations after TRH administration as compared to those who conceived. We conclude that occult hyperprolactinemia may be a cause of infertility in patients with endometriosis.