Phosphate retention, hyperphosphatemia, low serum calcium ion, deficiency of 1α,25(OH)2D deficiency, elevated levels of PTH, intestinal calcium malabsorption, and the reduction of vitamin D receptors (VDRs) and calcium-sensing receptors (CaSRs) in the parathyroid glands play a role in the development of secondary hyperparathyroidism [17,28,29,30,31,32,33]. This evidence concerns the gene PTH and secondary hyperparathyroidism.