Objective: The aim of this study was to investigate the possible effect of prolactin on the metabolism of androgens and estrogens in patients with prolactinoma. To accomplish this, prolactin, urinary androgen, and estrogen metabolite levels were determined. In order to indirectly evaluate the possible involvement of enzymes, the concentration ratios of precursor metabolite to product metabolite were also compared with controls. Methods: Urine samples were obtained from 27 female patients with prolactinoma (macro, micro, and idiopathic) and from 31 age-matched normal female subjects. Urinary metabolites of 21 androgens and corticoids and 20 estrogens were analyzed by a gas chromatography-mass spectrometry system. Results: In patients with prolactinoma, urinary 17-ketosteroids, and all estrogen metabolite concentrations were elevated. The ratios of Δ5/Δ4-steroids and 5β/5α-hydrogensteroids were higher in the patients with prolactinoma than in normal female controls. In addition, no significant differences between patients and controls were observed in the precursor metabolite to product metabolite ratios relating to estrogen metabolism. Conclusion: Our data suggests that enhanced PRL levels have a direct effect on urinary steroid secretion and metabolism, probably due to lowered activities of 5α-reductase and 3β-hydroxysteroid dehydrogenase in the patients with prolactinoma.
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