Influence of serum prolactin on semen characteristics and sperm function

The role of serum prolactin (sPRL) in male infertility is still unclear. For assessing the clinical significance of prolactin determination during infertility investigation, serum samples of 204 males attending the Infertility Clinic of Heidelberg were examined during a 1-year period. None of the patients exhibited galactorrhoea or complained of impotence. Results were correlated with age, duration of infertility, sperm count, motility, morphology, viability, and other parameters of routine sperm analysis and postcoital testing (PCT). Additionally, in vitro sperm penetration testing (SCMPT) in cervical mucus of partners and donors was performed as an important measure of functional sperm capacity. The subsequent pregnancy rate was determined after 6 months. Prolactin levels ranged from 1.4 to 24.7 ng/mL, with a median of 5 ng/mL. Only one patient had prolactin levels out of the normal range (greater than 20 ng/mL). No significant correlation of sPRL concentration was found with results of semen analysis, PCT outcome, or SCMPT. The functional sperm capacity was better in the groups of patients with sPRL above the median level (P less than .005). No significant difference in pregnancy rate was found between the high (greater than 5 ng/mL) and low (less than or equal to 5 ng/mL) prolactin groups; these were 20% and 26%, respectively. The results suggest that routine screening of asymptomatic male patients during infertility investigation for sPRL concentration is not helpful for assessing fertility prognosis. Prolactin should be preferentially determined in patients with clinical symptoms of hyperprolactinemia to exclude pituitary adenoma.