Abstract: 【Abstract】Objective To investigate the calcium-phosphate metabolic condition in pre-dialysis patients with chronic kidney disease (CKD), and to obtain useful information about the diagnosis and treatment of bone metabolic disorders.  Methods We compared the levels of serum calcium, phosphate, intact parathyroid hormone (iPTH) and alkaline phosphatase (AKP), and the prevalence of secondary hyperparathyroidism (SHPT), and performed correlation analysis for these parameters among patients with different stages of CKD.  Results In CKD patients at stage 3, 4 and 5, serum calcium was 8.62±0.69, 8.48±1.31 and 7.69±1.25 mg/dl, respectively; serum phosphate was 4.37±1.33, 5.50±1.57 and 7.59±2.41 mg/dl, respectively; calcium-phosphate product was 37.64±11.09, 47.13±14.17 and 60.53±21.87 mg2/dl2, respectively; serum AKP was 146.62±130.56, 125.33±92.31 and 131.76±68.85 U/L, respectively; serum iPTH was 155.77±198.95, 353.6±381.93 and 434.37±351.03 pg/ml, respectively. In the patients at stage 3, 4 and 5, the prevalence of hypocalcemia was 22.2%, 29.4% and 68.3%, respectively; the prevalence of hyperphosphatemia was 15.6%, 56.8% and 76%, respectively; the prevalence of SHPT was 47.6%, 56.8% and 80.4%, respectively. With the progression of chronic kidney disease, serum calcium gradually decreased, serum levels of phosphate, calcium-phosphate product and intact parathyroid hormone (iPTH) increased, and the prevalence of SHPT became higher (P＜0.05). Serum iPTH level was negatively correlated with serum calcium and glomerular filtration rate (GFR), and was positively correlated with serum phosphate and calcium-phosphate product. However, serum AKP level was found to have no correlation with other biochemical parameters. Conclusion Metabolic disorders emerge early in CKD patients and deteriorate in association with the progression of CKD. Early intervention should be given to improve their outcomes.

Key words: Chronic kidney disease, Secondary hyperparathyroidism, Glomerular filtration rate, Calcium and phosphate metabolism