The function of the adenohypophyseal-gonadal axis in haemodialyzed male patients is modified: the serum testosterone level is low, and the gonadotropin levels are increased. The pathogenetic role of secondary hyperparathyroidism in this disorder has not previously been defined. The area under the curve (AUC) and the secretion kinetics of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone after administration of LH-releasing hormone were examined in 7 dialyzed men with secondary hyperparathyroidism (mean age 36.2, range 20-47 years) before and 3 and 6 months after parathyroidectomy (PTX). The operation was successful in all 7 patients, as intact parathyroid hormone declined markedly during both postoperative periods as compared with the values before PTX: 81 +/- (SEM) 34 and 138 +/- 57 ng/1 versus 965 +/- 116 ng/l (p < 0.01 and p < 0.0l). The testosterone AUC prior to PTX (63 +/- 115 nmol/l x min) and 3 months (-4 +/- 36 nmol/l x min) and 6 months after PTX (-62 +/- 69) did not differ significantly, as was the case with LH AUC (1,110 +/- 223 and 1,214 +/- 331 and 1,020 +/- 314 U/l x min, respectively) and follicle-stimulating hormone AUC (525 +/- 334 and 634 +/- 347 and 533 +/- 264 U/l x min, respectively). The secretion kinetics of all three hormones was atypical as compared with healthy men of similar age, but it did not change after PTX. There were no correlations between the sexual indicators and parathyroid hormone, 1,25(OH)2D3, calcium, or phosphate during the individual periods. These findings indicate that secondary hyperparathyroidism is probably not involved in the dysfunction of the adenohypophyseal-gonadal axis in dialyzed men.