腎骨病變之病理變化及治療

Pathologic Change and Treatment of Renal Osteodystrophy

腎骨病變為慢性腎衰竭病患常見之併發症，其傳統之分類根據骨週轉速率之不同分為高週轉型骨病變（副甲狀腺增生型骨病變），及低週轉型骨病變（包括混合型腎骨病變，鋁中毒引起之骨軟化症，及再生不良型骨病變）。在治療上，副甲狀腺增生型骨病變需注意飲食中磷的控制，使用含鈣磷結合劑以預防低血鈣症，及使用活性維生素D製劑以抑制副甲狀腺素之製造與分泌。鋁中毒的治療，需避免再給予任何含鋁之磷結合劑，維持透析用水鋁含量在安全值以下，並使用靜脈注射鋁螯合劑(desferrioxamine)治療。至於再生不良型骨病變之預防，則需避免過度使用高鈣透析，避免過度服用含鈣磷結合劑或維生素D製劑而造成過度抑制副甲狀腺，並可使用低鈣透析來刺激副甲狀腺。最近有些新藥上市，如不含鋁且不含鈣之磷結合劑sevelarmer hydrochloride，及不造成高血鈣症之維生素D製劑Zemplan。而有些新藥仍在臨床試驗中，如不造成高血鈣症之維生素D製劑22-oxacalcitriol，doxercalcitriol等及不造成高血鈣症且可刺激鈣感受體進而抑制副甲狀腺之擬鈣劑R-568。這些新藥將來可望增加臨床用藥的選擇。

Renal osteodystrophy is a common complication in patients with chronic renal failure. According to difference in bone turnover rates, it is classified into high turnover renal osteodystrophy (hyperparathyroid bone disease), and low turnover renal osteodystrophy (including mixed uremic osteodystrophy, aluminum-induced osteomalacia and adynamic bone disease). Prevention and treatment of hyperparathyroid bone disease includes dietary phosphate control, the administration of phosphate binder, supplementation with calcium, and administration of calcitriol. To prevent aluminum-related osteomalacia, dialysate aluminum content should be kept under a safe level and use of aluminum-containing phosphate binder should be avoided. To prevent adynamic bone disease, the administration of high concentration of dialysate calcium and the overzealous use of oral calcium and calcitriol supplement should be avoided. In patients with hypoparathyroidism, low calcium dialysate could be tried in order to stimulate the parathyroid gland. Recently, some new drugs have been approved for use in these patients, such as aluminum-free and calcium-free phosphate binder sevelamer hydrochloride, and non-calcemic vitamin D derivative zemplar. Some new drugs are still being evaluated in clinical trials, such as non-calcemic vitamin D derivative 22-oxacalcitriol and calcemimetics R-568. These new drugs may allow clinicians more selections to therapies that have fewer side effects in clinical practice.