The relationship between gonadotrophins, gonadal hormones and bone mass in men.

OBJECTIVE

Inhibin A and B (Inh A and B), activin A (Act A) as well as FSH may play an important role in bone turnover in perimenopausal women. Data in men are lacking. The aim was to investigate the relationship between circulating concentrations of Inh B and Act A and FSH/LH/testosterone (T) and their contribution to bone mineral density (BMD) in a male population.

DESIGN AND SUBJECTS

Cross-sectional case-control study of 156 men, 63 with osteoporosis and 93 controls, aged (mean [SD]) 57.7 [13.7] years.

MEASUREMENTS

Areal (aBMD) was measured at the femoral neck, total hip and lumbar spine. Volumetric BMD (vBMD) was calculated at the femoral neck and lumbar spine. Risk factors were assessed including the measurement of LH/FSH/T, Inh B and Act A.

RESULTS

After correction for age and body mass index (BMI), associations were found between Inh B and FSH (beta regression coefficient beta = -0.326; P < 0.0001), T (beta = -0.36; P = 0.019) and Act A (beta = -0.4; P = 0.007) and between Inh B and LH (beta = 0.23; P < 0.0001) in all patients. The controls had higher Inh B concentrations compared to the cases (Inh B: controls: 139 [86] pg/ml vs. cases 88 [51] pg/ml; P = 0.005). Act A tended to be lower in the controls (Act A: controls 0.63 [0.24] ng/ml vs. cases 0.75 [0.4] ng/ml; P = 0.056). Univariate regression analyses showed a positive association between Inh B and BMD (P < 0.01) at the lumbar spine and total hip. In contrast a negative association was seen between FSH and BMD at the lumbar spine and femoral neck (P < 0.01). In a partial multivariate regression model that included the gonadal factors only, a positive association was seen between Inh B and BMD at the hip (beta = 0.088; P = 0.04). When all hormones including the gonadotrophins were entered in a full multivariate model, FSH and LH were found to be better predictors of BMD than Inh B or Act A in the controls and cases.

CONCLUSIONS

These data suggest that the gonadal peptides and gonadotrophins may play a role in the maintenance of bone mass in men. Future confirmatory longitudinal studies are needed.