シナカルセトの二次性副甲状腺機能亢進症改善が腎性貧血に及ぼす効果 Effect of improvement of secondary hyperparathyroidism using cinacalcet on renal anemia

〔目的〕エリスロポエチン抵抗性貧血の原因の一つとして、二次性副甲状腺機能亢進症が知られている。シナカルセトは2008年に日本で使用可能となった二次性副甲状腺機能亢進症に対する新しい薬剤である。今回、シナカルセトの貧血に対する効果を検討した。〔方法〕シナカルセトを使用した18名を対象とし、開始4ヵ月後の血清i-PTH 300 pg/ml以下をeffective群、それ以上をnon-effective 群と分け、ヘモグロビン、鉄飽和率、フェリチン、CRPを使用前と4ヵ月後で比較した。赤血球生成刺激剤はダルベポエチン (DPO)を使用し、その投与量も比較した。〔結果〕12名 (66.7 %) がeffective 群で、シナカルセト開始4ヵ月後に血清i-PTH値は777 ± 292 pg/dlから200 ± 68 pg/dl (p=0.002)に、DPOの使用量は28.3 ± 15.9 μg/weekから16.9 ± 15.8 μg/week (p=0.027)に低下したが、ヘモグロビン値は10.2 ± 1.2 g/dlから10.6 ± 0.9 g/dlと変化なかった。non-effective群ではヘモグロビン値10.1 ± 1.4 g/dlから10.1 ± 1.4 g/dlと変化なく、DPOの使用量は26.7 ± 20.7 μg/weekから28.3 ± 22.3 μg/weekと低下を認めなかった。両群とも鉄飽和率、フェリチン、CRPに変化を認めなかった。〔結論〕シナカルセトは二次性副甲状腺機能亢進症を改善することにより貧血を改善する可能性がある。

Objective: Secondary hyperparathyroidism (SHPT) is known to inhibit the erythropoiesis. To determine the effect of cinacalcet treatment on renal anemia, we investigated the response to erythropoiesis-stimulating agents (ESA) in hemodialysis patients started on cinacalcet. Methods: Eighteen patients on hemodialysis treated with cinacalcet were enrolled in this study. We divided the patients according to the response of the i-PTH level to treatment. The "effective" group was defined as the group in which the serum i-PTH level decreased to below 300 pg/ml, the "non-effective group" was above 300 pg/ml at 4 months after the initiation of cinacalcet. We compared serum levels of c-reactive protein (CRP), iron (Fe), the total iron binding capacity (TIBC), ferritin and hemoglobin before and at 4 months after the start of cinacalcet therapy. Darbepoetin Alfa was used as the ESA. We also compared the required dose of ESA. Results: Twelve patients (66.7 %) were in the "effective" group. Four months after the start of cinacalcet therapy, the serum PTH level fell from 777 ± 292 to 200 ± 68 pg/dl (p=0.002), the mean dose of darbepoetin alfa (DPO) decreased from 28.3 ± 15.9 to 16.9 ± 15.8 μg/week (p=0.027), nonetheless, no significant difference was observed in relation to the hemoglobin level (10.2 ± 1.2 to 10.6 ± 0.9 g/dl) in the "effective" group. In the "non-effective" group, there were no statistically significant changes in the serum levels of i-PTH, or hemoglobin, or the dose of DPO. There were no changes in the serum level of CRP, ferritin or the Fe saturation in both groups. Conclusions: Improvement of SHPT using cinacalcet may effective in increasing the response to ESA in renal anemia.