Methods for modulating serum phosphorus levels are described, wherein calcimimetic agents are administered to a subject in need thereof. In one embodiment, the compound is cinacalcet, and in other embodiments the compound is comprised of a contiguous sequence of subunits, X1—X2—X3—X4—X5—X6—X7, wherein the X1 subunit comprises a thiol-containing moiety and the distribution of charge on the X2-X7 subunits. The compound, when administered at selected times to a patient undergoing dialysis, lowers serum phosphorus levels, relative to pre-dosing levels, and achieves a sustained reduced level for a period of time after administration.