Low transforming growth factor-beta1 serum levels in idiopathic male osteoporosis

Although the etiology of osteoporosis is different between men and women, the underlying pathophysiological mechanism is similar, namely an absolute or relative increase in bone resorption, leading to progressive bone loss. Transforming growth factor (TGF)-beta1 is a growth factor in human bone, which is produced by osteoblasts, and which has various effects on osteoclasts and osteoblasts. The aim of our study was to determine serum TGF-beta1 levels in male patients with idiopathic osteoporosis.

Twenty five males with idiopathic osteoporosis and 25 age-matched controls were studied. Osteoporosis was defined by a T score of <-2.5 in the lumbar spine or at the femoral neck. We measured levels of TGF-beta1, estradiol, total and bioactive testosterone. Various markers of bone remodeling were also measured.

TGF-beta1 was significantly lower in osteoporotic patients than in controls (3.706 ng/dl, 25-75 percentiles: 2.81-5.33 vs 8.659 ng/dl, 25-75 percentiles: 4.837-11.835; p=0.000). Moreover, TGF-beta1 levels were positively correlated with bone mineral density (BMD) at the femoral neck (r=0.439, p=0.028), and at the lumbar spine (r=0.41, p=0.042). No correlation was found between serum estradiol, testosterone and TGF-beta1 levels.

Serum TGF-beta1 levels are depressed in osteoporotic men and are positively correlated with hip and spine BMD. The results of our study suggest that TGF-beta1 may play a role in the pathogenesis of idiopathic male osteoporosis.