PITUITARY-TESTICULAR FUNCTION IN NEPHROPATHIC CYSTINOSIS

Objective: To evaluate reproductive function in patients with cystinos is and in renal transplant recipients without cystinosis. Design: Cros s-sectional study. Setting: Clinical Center, National Institutes of He alth. Patients: Ten male patients, 15 to 28 years old, with nephropath ic cystinosis and renal allografts formed the study group; 11 renal tr ansplant recipients who had a primary renal disorder other than cystin osis and were matched with study patients for age and renal function s erved as the control group. Measurements: Tanner staging, serum gonado tropin determinations, and testosterone and testosterone-binding globu lin assessments. Selected patients also had a human chorionic gonadotr opin (HCG) stimulation test, a gonadotropin-releasing hormone (GnRH) s timulation test, and serial sampling for luteinizing hormone (LH). Mai n Results: Although testosterone levels were within normal limits in 7 of 10 patients with cystinosis, the mean testosterone level in patien ts with cystinosis was 11.5 +/- 2.0 nmol/L compared with 24.2 +/- 3.0 nmol/L in control patients (P < 0.005). No patient with cystinosis rea ched Tanner stage 5 (full pubertal development), whereas 9 of 11 contr ol patients did. Seven of 10 patients with cystinosis had elevations i n LH or follicle-stimulating hormone (FSH) levels, suggesting testicul ar failure. These patients also had normal LH and FSH responses after GnRH stimulation, increased LH pulse frequency, and reduced testostero ne response after HCG stimulation. In comparison, only 3 of 11 control patients had minimally elevated gonadotropin levels, and all 11 had n ormal testosterone levels. Microscopic testicular examination in one p atient showed cystine crystals, germinal dysplasia, increased fibrosis , and Leydig cell hyperplasia. Conclusions: Abnormalities in the pitui tary-testicular axis are common in male patients with cystinosis. Thes e changes appear to be related to the disease cystinosis and not to tr eated renal failure per se.