HYPERPROLACTINEMIA AND VERAPAMIL - PREVALENCE AND POTENTIAL ASSOCIATION WITH HYPOGONADISM IN MEN

OBJECTIVE Verapamil has been associated with hyperprolactinaemia, but there have been no population-based studies. Our objective was to dete rmine the prevalence and degree of hyperprolactinaemia associated with verapamil in the clinical setting. DESIGN Observation with cross-sect ional and longitudinal components in the setting of an urban teaching hospital and its satellite out-patient clinics. PATIENTS Male out-pati ents excluding those taking other drugs known to raise PRL, renal fail ure and known primary hypothyroidism (1265 eligible subjects). Control subjects were drawn from eligible out-patients not taking verapamil. MEASUREMENTS Serum PRL levels, frequency of persistent hyperprolactina emia and total testosterone levels. RESULTS Prolactin levels were obta ined in 449 subjects on verapamil (35.5% response rate) and 166 contro ls. The proportions of individuals with hyperprolactinaemia (PRL > 460 mU/l) were 0.085 and 0.030 in the verapamil and control groups, respe ctively (P = 0.012, chi(2)-test). The mean (+/- SD) serum PRL levels w ere 267 +/- 205 and 203 +/- 118 mU/l in the verapamil and control grou ps, respectively (P < 0.001, independent t-test). Of the 38 patients w ith previously determined elevated PRL levels, follow-up data were obt ained in 25 (65.8%); one was found to have a pituitary adenoma and was excluded from the analysis, Fifteen of the 24 were still on verapamil (Group 1) and 14 (93.3%) continued to be hyperprolactinaemic. In 9 pa tients verapamil had been discontinued (Group 2) and all had normal PR L levels. Continued verapamil use was associated with persistent hyper prolactinaemia (odds ratio > 120, P < 0.00001). The mean +/- SD serum testosterone levels at follow-up were significantly lower in Group 1 ( 6.16 +/- 2.52 nmol/l) than in Group 2 (9.42 +/- 3.92 nmol/l, P = 0.029 , independent t-test), CONCLUSIONS The prevalence of hyperprolactinaem ia associated with verapamil use in this study of male outpatients was 8.5% (95% CI 5.9-11.1%). The persistence of hyperprolactinaemia when verapamil was continued (Group 1) and the return to normal PRL levels when verapamil was discontinued (Group 2) confirm verapamil's causal r ole in the development of hyperprolactinaemia, While low testosterone levels were common in both groups, testosterone revels were lower in p atients on verapamil. Our data suggest that screening for hyperprolact inaemia should be considered in mate patients taking verapamil.