The role of androgens or growth factors in the bone resorption process in recent spinal cord injured patients: a cross-sectional study.

STUDY DESIGN

This cross-sectional study compared the androgen and growth factor profiles and the bone turnover of patients with spinal cord injury (SCI) versus able-bodied controls (AB).

OBJECTIVE

Determine whether androgens, GH, or either IGF-I or IGFBP-3, are implicated in bone turnover alteration in patients with recent SCI.

SETTING

Propara Center, Montpellier, France.

METHODS

In all, 16 men (31.3 years) with complete SCI, seven paraplegics and nine tetraplegics, who had sustained injury an average of 3 months earlier, and 12 AB who served as controls (27.5 years) participated. Androgens, growth hormone and its mediators were investigated. The bone resorption process was evaluated by urinary and plasma type I collagen C-telopeptide (CTXu, CTXp), while bone formation was evaluated by osteocalcin (OC) and bone alkaline phosphatase.

RESULTS

Total testosterone (TT) and the free androgen index (FAI) were significantly lower in the SCI patients, whereas FSH was significantly higher (P<0.05). These hormonal variations were not related to the level of neurological lesion. There was no significant difference in GH, IGF-I, or IGFBP-3 levels. CTXu and CTXp indicated high bone resorption activity in the SCI patients (P<0.05). Regarding bone formation markers, only OC was affected by neurological lesion (P<0.05). Basal hormone levels did not correlate with markers of bone turnover.

CONCLUSION

The high bone resorption process observed in SCI patients did not seem directly related to testicular endocrine abnormalities or an altered growth factor profile. Nevertheless, the reduced TT and FAI levels could be aggravating factors in the development of acute bone loss.