Prolactin hyperstimulation in response to thyrotropin-releasing hormone in patients with endometriosis

In order to clarify the role of hyperprolactinemia as a possible cause of infertility in patients with endometriosis, baseline serum prolactin (PRL) concentrations and the PRL response to thyrotropin-releasing hormone (TRH) stimulation were measured in 14 infertile women with endometriosis and in 13 normal, fertile women. Baseline PRL concentrations were 2-fold greater in the endometriosis group than in normal subjects, but the mean values did not differ significantly. Following TRH administration, a significant increase in peak PRL concentrations was observed in patients with endometriosis (211.5 +/- 34.9 ng/ml) when compared with corresponding values in control subjects (117.1 +/- 14.9 ng/ml, P less than 0.05). This hypersecretory state was selective for PRL because no significant differences between the baseline and TRH-stimulated thyroid-stimulating hormone (TSH) concentrations or total serum thyroxine concentrations were observed. In summary, some infertile women with endometriosis exhibit a greater capacity for PRL secretion than normal women. These results suggest that relative hyperprolactinemia may be responsible for the infertility associated with endometriosis, and that PRL suppression may be indicated in these patients.