Hypoprolactinemia: a new clinical syndrome in patients with sexual dysfunction.

INTRODUCTION: The physiological role of prolactin (PRL) in male sexual behavior is poorly understood. Conversely, the association between PRL pathological elevation in both reproductive and sexual behavior is well defined.

AIM: The aim of the present study is to assess the correlates of normal PRL (PRL < 735 mU/L or 35 ng/mL), in male subjects consulting for sexual dysfunction.

METHODS: A consecutive series of 2,531 (mean age 52.0 +/- 12.9 years) subjects was investigated. Patients were interviewed using the structured interview on erectile dysfunction (SIEDY), a 13-item tool for the assessment of erectile dysfunction (ED)-related morbidities. Middlesex Hospital Questionnaire was used for the evaluation of psychological symptoms.

MAIN OUTCOME MEASURES: Several hormonal (testosterone, thyroid stimulation hormone, and PRL) and biochemical parameters (glycemia and lipid profile) were studied, along with penile Doppler ultrasound (PDU) and SIEDY items.

RESULTS: After adjustment for confounders anxiety symptoms decreased across PRL quartiles (I: <113 mU/L or 5 ng/mL; II: 113-156 mU/L or 5.1-7 ng/mL; III: 157-229 mU/L or 7.1-11 ng/mL; IV: 229-734 mU/L or 11.1-34.9 ng/mL). Patients in the lowest PRL quartile showed a higher risk of metabolic syndrome (MetS; odds ratio [OR] = 1.74 [1.01-2.99], P < 0.05), arteriogenic ED (peak systolic velocity at PDU < 35 cm/sec; OR = 1.43 [1.01-2.03], P < 0.05), and premature ejaculation (PE; OR = 1.38 [1.02-1.85]; P < 0.05). Conversely, comparing subjects with PRL-secreting pituitary adenomas (N = 13) with matched controls, no significant difference was observed, except for a higher prevalence of hypoactive sexual desire in hyperprolactinemia.

CONCLUSIONS: Our findings demonstrate that, in subjects consulting for sexual dysfunction, PRL in the lowest quartile levels are associated with MetS and arteriogenic ED, as well as with PE and anxiety symptoms. Further studies are advisable in order to confirm our preliminary results in different populations.