Pituitary-testicular and pituitary-thyroid axes in spinal cord-injured males

Thirty spinal cord-injured (SCI) males were studied for evaluation of their pituitary-testicular and pituitary-thyroid axes using combined luteinizing hormone-releasing hormone (LHRH) and thyrotropin-releasing hormone (TRH) tests and electroejaculated semen analyses. Thirty age-matched normal male volunteers served as controls. There were four subjects with low serum triiodothyronine (T₃) levels, one with elevated serum follicle-stimulating hormone (FSH) level, eight with elevated serum testosterone levels, and 11 with elevated serum prolactin levels. There were significantly elevated luteinizing hormone (LH) responses to LHRH in SCI subjects when compared with normal controls. There were 16 (53.3%) SCI subjects who had exaggerated and/or prolonged LH responses. Among them, six subjects also had elevated FSH responses. There were eight and four subjects whose thyrotropin (TSH) and prolactin responses to TRH were exaggerated, respectively. Marked impaired motility was observed in 56 electroejaculated semen samples from 16 SCI subjects. There was a significant correlation between LH and total sperm count. Our data suggest that there is a reduced central dopaminergic tone in SCI subjects.