An increase in serum PTH (parathyroid hormone) levels in chronic kidney disease secondary to secondary hyperparathyroidism is an unavoidable complication accompanying end-stage renal disease due to the prolonged decline in serum Ca2+ and 1,25(OH) 2 D (1,25-dihydroxyvitamin D3) concentrations due to renal failure [33]. This evidence concerns the gene PTH and secondary hyperparathyroidism.