Secondary hyperparathyroidism (HPT) is common in people with end stage renal disease (kidney disease). Patients with secondary HPT often have enlarged parathyroid glands in the neck and as a result often have elevated parathyroid hormone (PTH) levels . Patients with secondary HPT may have bone disease (osteodystrophy). Cinacalcet has been used to decrease PTH levels in patients with secondary HPT. Patients with secondary HPT may have bone disease (osteodystrophy). This bone disease may cause bone pain, fractures, and poor formation of red blood cells. The purpose of this study is to evaluate effects of cinacalcet on markers of bone turnover in patients with kidney disease who are receiving dialysis.