12 month prospective study of 23 patients with severe SHPT. Two treatment regimens were considered: standard treatment (m 0) and standard treatment plus cinacalcet (m 12). Four consequences of inadequate control of SHPT were registered: parathiroid hormone (PTH), Calcium (Ca), Phosphorus (P) and the Ca x P product serum levels. Treatment effectiveness was measured as percentage of patients who achieved treatment goal according to each indicator: PTH<800 pg/mL, PTH between 150 and 300 pg/mL, Calcium<9