Early Initiation of Cinacalcet for the Treatment of Secondary Hyperparathyroidism in Hemodialysis Patients: A Three-Year Clinical Experience

摘要

Despite the availability of standard therapy (vitamin D sterols and phosphate binders) for the treatment of secondary hyperparathyroidism (SHPT) in hemodialyzed (HD) patients, a significant percentage of patients still fail to achieve targets recommended by the Kidney Disease Outcomes Quality Initiative (K/DOQI) of the National Kidney Foundation for parathyroid hormone (PTH), calcium, and phosphorus. The calcimimetic cinacalcet (CN) has been shown to be an effective treatment for SHPT, significantly reducing serum PTH while simultaneously lowering calcium, phosphorus, and calcium–phosphorus product levels, thus increasing the proportion of patients achieving the K/DOQI targets for bone mineral parameters. The aim of this study was to evaluate if early treatment with CN had beneficial effects in HD patients with mild-to-moderate SHPT in whom conventional treatments had failed to achieve NKF-K/DOQI targets for PTH, serum-corrected calcium, and phosphorus while minimizing the risk of paradoxical hypercalcemia and/or hyperphosphatemia. Clinical practice data were collected monthly, starting from 6 months prior to, and up to 36 months after, the start of CN therapy. CN was started at a dose of 30?mg daily or every other day, and titrated thereafter to achieve intact PTH (iPTH) <300?pg/mL. The dose of concomitant vitamin D and phosphate binders were also adjusted in order to achieve K/DOQI targets. Data from 32 patients were collected, 28 of whom had been treated with CN for at least 36 months at the time of data analysis. At baseline, patients had serum iPTH >300?pg/mL (570?±?295?pg/mL) and/or serum-corrected calcium >9.5?mg/dL. CN induced significant decreases in iPTH, calcium, and calcium–phosphorus product with respect to baseline levels. The percentage of patients within K/DOQI target levels at baseline, 12, 24, and 36 months was 0, 81.2, 83.3, and 86.2% for iPTH; 34.4, 65.6, 86.6, and 89.6% for serum-corrected calcium; 40.6, 56.2, 69.6, and 72.4% for phosphorus; and 37.5, 62.5, 80, and 82.7% for calcium–phosphorus product. The mean dose of CN at the end of the observation period was 38?mg/day. The mean dose of concomitant medication (calcitriol, Al-containing phosphate binders, and sevelamer) decreased from baseline to 36 months. Early treatment with CN in HD patients with SHPT increases the proportion of patients achieving and maintaining K/DOQI targets with a low dose of CN (38?mg/day). These results suggest that the metabolic control obtained with low-dose CN administered early in the course of SHPT can be maintained or increased over time.