Decreased levels of testosterone and gonadotrophins in men with long-standing tetraplegia

Study Design: Blood samples were frequently collected during a 24-h period from six tetraplegic men. The results were compared with those of eight able-bodied controls. Objective: Previous studies have reported conflicting results regarding the plasma concentrations of testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in tetraplegia. The objective of this study was to examine the pituitary-gonadal axis by determining the plasma concentrations and circadian variations of these hormones in men with long-standing tetraplegia. Setting: Sunnaas Hospital, Norway. Methods: The plasma concentrations of hormones were measured with standardized assays. Results: All three hormones and free testosterone index were decreased in the tetraplegic subjects compared with the able-bodied controls (P < 0.05). We also determined the morning levels of hormones with regulatory effects on testosterone, LH and FSH. Whereas plasma leptin was significantly higher in the tetraplegic group, no significant differences in the morning plasma values for insulin, SHBG, GH or IGF-1, or in the 24-h urine concentrations of cortisol were detected between the two groups. The plasma concentration of LH displayed a circadian variation (P < 0.05) in the tetraplegic group, but not among the able-bodied. No circadian variation was noted for the plasma concentrations of testosterone and FSH in either group. Conclusion: Our data indicate that, over time, tetraplegic male subjects might be at risk of developing hypogonadism.