Bone mass and hormone analysis in patients with spinal cord injury: evidence for a gonadal axis disruption.

CONTEXT: Bone loss is a constant finding in patients with spinal cord injury (SCI).

OBJECTIVE

We sought to evaluate potential modifiable factors that could lead to bone loss in complete motor paraplegia by examining gonadal axis hormones, vitamin D status, and bone markers.

DESIGN

This is a cross sectional.

SETTING

It includes SCI Outpatient.

PATIENTS AND OTHER

PARTICIPANTS

Twenty-nine chronic male patients with SCI were compared with 17 age-matched, able-bodied men.

MAIN OUTCOME MEASURE: The bone mineral density (BMD) of lower limbs and lumbar spine were measured using dual x-ray absorptiometry. Parathormone, 25-hydroxyvitamin D [25(OH)D], collagen type I C-terminal telopeptide (CTX), and sexual hormone were measured.

RESULTS

Patients with SCI had lower BMD at the inferior limbs sites. CTX showed an inverse relationship with the time since injury. Patients had lower free T levels (SCI, 12.00 ± 2.91 vs controls, 19.51 ± 5.72; P ≤ .001), and the majority (72%) had normal/low levels of gonadotropins. Low T, however, was not related to low bone mass in patients with SCI. In the controls, the 25(OH)D level was positively correlated with the T and with the lumbar spine BMD, but these correlations were not observed in the SCI.

CONCLUSIONS

Impairment of testicular function after SCI was indicated by the low levels of T and the loss of correlation between T and 25(OH)D levels; this correlation was present in the able-bodied controls. Inappropriate levels of gonadotropins were identified in most patients, featuring a hypogonadotropic hypogonadism and suggesting a disruption of the pituitary-gonadal axis. T concentrations might not be an effective target for bone loss therapy.