Background: secondary hyperparathyroidism (SHPT), a complication of chronic kidney disease (CKD) and is characterized by not only increased serum levels of intact parathyroid hormone (iPTH), but also may cause skeletal and cardiovascular complications. Deficiency of calcitriol (1, 25-hydroxy vitamin D) caused by impaired renal function, a main factor in the pathogenesis and pathophysiology of seco...