A Study of Maintenance Therapy After Intravenous Maxacalcitol for Secondary Hyperparathyroidism

Chronic kidney disease (CKD) causes various bone mineral disorders, which have recently been named CKD mineral and bone disorder (CKD-MBD). CKD-MBD presents a spectrum of skeletal abnormalities ranging from high bone turnover state such as osteitis fibrosa, which is seen with SHPT, to states of low bone turnover, which includes osteomalacia and adynamic bone disease. This disease not only increases the risk of cardiovascular disease and mortality, but also increases the risk of fracture. Therefore, it is important to correct the serum inorganic phosphorus (Pi), calcium (Ca) and parathyroid hormone (PTH) levels in dialysis patients, to achieve both appropriate bone turnover and to improve mortality.

The Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines recommend that the target range of iPTH level for vitamin D therapy should be set at 150-300 pg/mL. In Japan, the mortality risk was significantly lower in the group of patients with iPTH levels < 120 pg/mL than in the standard group set at 180 pg/mL < iPTH < 360 pg/mL, and lowest in the group of patients with 60 pg/mL < iPTH < 120 pg/mL . Based on these findings, Japanese guideline recommend that the target range of iPTH should be set at 60-180 pg/mL .

The efficacies of various oral and intravenous vitamin D preparations for treating SHPT in hemodialysis patients have been reported. and oral or intravenous vitamin D pulse therapy has been clinically applied, especially for patients with severe SHPT.

Up to now, the effectiveness of an oral daily alfacalcidol on SHPT has been confirmed at the dose of 0.25-0.5 μg /day (average 0.364μg /day), 0.5 μg /day, and 1.0 μg /day. The effective dose of OCT has also been verified, and furthermore, it has also been reported that intravenous vitamin D was more effective than oral vitamin D for suppressing PTH secretion. Accordingly, at present intravenous vitamin D therapy is the standard treatment for SHPT, and there are established protocols with regard to dosage and administration. However, no protocols have been established for maintenance therapy using intravenous or oral vitamin D preparations after the control of iPTH target range has been achieved.

Therefore, the present study compared the efficacy of two maintenance therapy protocols for patients with SHPT who responded to initial OCT therapy, resulting in the control of iPTH to <150pg/mL. One was oral administration of alfacalcidol (an oral vitamin D preparation) at a dose of 1.0 μg/day (higher-dose group) and the other was at a dose of 0.25 μg/day (lower-dose group), both of which are clinically effective doses for HD patients with SHPT.