When sevelamer hydrochloride is used as a phosphate binder instead of the more common calcium carbonate, the PTH rises. This has been observed in many cases and makes it more difficult for practical use. However, considering the calcium load, the excessive dosing of calcium carbonate must be avoided. With that in mind, we divided the i-PTH in groups of 100 pg/mL and tested the changes in i-PTH value, P value, the adjusted Ca value, and the product of Ca and P before and after a dosage of sevelamer hydrochloride. When the average i-PTH was under 100mg/mL 6 months before dosing, the sevelamer hydrochloride single dosage group showed an early rise in i-PTH after dosing, maintaining a higher level than the calcium carbonate combined dosage group. Therefore, it was concluded that the use of sevelamer hydrochloride alone as a phosphate binder is best. On the other hand, the group with an average i-PTH over 100 pg/mL 6 months before dosing showed a rise of i-PTH that went over the K/DOQI guideline with a single dosing of sevelamer hydrochloride. Therefore, we concluded that using both sevelamer hydrochloride and calcium carbonate for phosphate binder is best.