Prolactin response to thyrotropin-releasing hormone in children with gynecomastia, premature thelarche and idiopathic precocious puberty.

Plasma prolactin (PRL) response to synthetic thyrotropin-releasing hormone (TRH) was studied in six patients with pubertal gynecomastia, five patients with premature thelarche and nine female patients with idiopathic precocious puberty. The basal concentration of plasma PRL was higher (p less than 0.01) in pubertal gynecomastia as compared to control, while baseline plasma PRL levels in premature thelarche and idiopathic precocious puberty were similar to those in controls. Plasma PRL level after TRH in patients with pubertal gynecomastia was higher (p less than 0.01) than that in control, while plasma PRL responses to TRH in idiopathic precocious puberty and premature thelarche were comparable to those controls. The TRH-induced PRL release was more enhanced during treatment with cyproterone acetate (CA) than before CA therapy in four of five patients with idiopathic precocious puberty. These data suggest that the enhanced release of PRL may, at least in part, contribute to breast enlargement in pubertal gynecomastia and that seen in idiopathic precocious puberty and premature thelarche may not depend on the PRL secretion. The prolonged administration of CA enhances the PRL responsiveness to TRH.