| [ Summary ] |
The trace mineral zinc (Zn) is known to be related to bone metabolism and the pathogenesis of osteoporosis. It is also thought to decrease osteoclast-like cells, as shown in in vitro studies. In order to investigate the relationship between serum zinc levels and serum levels of tartrateresistant acid phosphatase (TRACP) 5b, the clinical markers of osteoclast activity, serum Ca, iP, Zn, TRACP-5b, bone alkaline phosphatase (BAP) and intact PTH were measured in 66 male patients receiving maintenance hemodialysis (HD) with intact PTH<800 pg/ml levels. Serum TRACP5b levels were positively correlated with serum intact PTH levels in all patients (r=0.490, p<0.0001). As PTH markedly increased osteoclastogenesis, we analyzed the correlation between serum TRACP-5b levels and serum Zn levels. The patients were categorized in descending order of serum intact PTH levels. In the patients with serum intact PTH<90 pg/ml, log (serum TRACP-5b) was not correlated with log (serum intact-PTH), but was negatively correlated with log (serum Zn) (p<0.05). Stepwise regression analysis (forward method) indicated only log (serum Zn) levels as being predictive of variable log (serum TRACP-5b) levels. While log (serum intact PTH), log (serum BAP), log (age), diabetes mellitus or the intravenous pulse therapy of vitamin D were excluded (r2=0.288, p=0.0229, β=-0.582). This is the first report demonstrating the negative correlation between serum Zn levels and serum TRACP-5b levels in HD patients, suggesting the physiological serum Zn levels may decrease the number of osteoclast-like cells. Serum Zn levels were 65.2±9.9 µg/dl (m±SD) and below the normal reference range in half of the patients. It is expected that Zn supplementation for HD patients may prevent excessive bone resorption. |