Korean Journal of Nephrology 1998;17(2):266-274.

혈액투석 환자에서 bone -specific aljaline phosphatase의 임상적 의의와 대사성 산혈증의 존재가 bone turn - over marker에 미치는 영향

박기령 , 강덕희, 이은영 , 최규복 , 윤견일

Abstract

Renal osteodystrophy is a leading cause of morbi- dity in patients with end stage renal disease(ESRD), including a diverse clinical spectrum and histologic lesions. Since the invasiveness and practical limita- tions of bone biopsy to diagnose the exact nature of bone disease in ESRD patients, many attempts have been made to investigate the biologic markers of bone disease. Bone-specific alkaline phosphatase(bAP) is localized in the plasma membrane of osteoblast to be involved in bone formation and skeletal minera- lization. This study was undertaken to evaluate the value of bAP in the diagnosis of renal osteody- strophy and to examine the correlation between bAP (Immunoassay, Metra, U.S.A.) and other known mar- kers of bone turn-over, total alkalilne phosphatase (tAP), intact parathyroid hormone(iPTH) and osteo- calcin in 49 HD patients(M:F 29:20, mean age 51 years, mean HD duration 57 months). We also evaluated the impact of metabolic acidosis, which is known to stimulate the osteoclastic activity and bone resorption, on plasma levels of these bone markers. The median value of bAP in HD patients was 30.1ng/ml with a distribution of 8.8-140.1ng/ml (normal 12-23ng/ml). There was a significant posi- tive correlation between the duration of HD and plasma levels of tAP, bAP, iPTH and osteocalcin. Significant positive correlaton was also observed between iPTH and other markers of bone turn- over-bAP, tAP and osteocalcin. bAP was correlated better with iPTH(r=0.8483, P<0.001) than tAP(r= 0.7588, P<0.01). In the patients group whose arterial blood bicarbonate below 20mEq/L(30 cases), plasma iPTH and bAP were significantly higher compared to the patients with arterial bicarbonate higher than 20mEq/L(19 cases). In conclusion, high bAP can be an useful marker of increased bone turn-over in HD patients. Increa- sed concentrations of iPTH and bAP in patients with metabolic acidosis(arterial bicarbonate below 20 mEq/L) may reflect an increased bone resorption with resultant increase in osteoblast activity. Howe- ver, a prospective study with alkali supplementation and bone biopsy will be necessary to define the exact role of metabolic acidosis in the development and progression of renal osteodystrophy.