Mineral and bone disorder in patients with chronic kidney disease: a cross - sectional single center study

Objective To investigate and analyze the mineral and bone disorder (MBD) in the patients with chronic kidney disease (CKD), reveal the change of related indexes of CKD-MBD. Methods A cross-sectional study was carried out in the First Affiliated Hospital of Harbin Medical University. From October 2011 to May 2014, 1318 inpatients and hemodialysis outpatients were enrolled. Parameters related to MBD, including serum phosphorus (P), total calcium (t - Ca), intact parathyroid hormone (iPTH) and alkaline phosphatase (AKP) were analyzed. Last, it was analyzed with multiple regression analysis to related factors of the secondary hyperparathyroidism (SHPT) in patients with CKD. Results Serum calcium, phosphorus and iPTH had no obvious abnormalities at the early stages of CKD [GFR＞60 ml•min-1•(1.73 m2）-1], and relatively stable before GFR＞30 ml•min-1•(1.73 m2)-1. After entering the CKD4 stage, serum phosphorus, iPTH increased sharply and serum calcium decreased obviously along with the decreased glomerular filtration rate (GFR). Serum P, t-Ca and iPTH levels were statistically significant in CKD 1 to 5D patients, respectively, serum P: (1.13±0.20) mmol/L, (1.14±0.22) mmol/L, (1.26±0.23) mmol/L, (1.48±0.34) mmol/L, (2.05±0.61) mmol/L and (2.08±0.58) mmol/L; serum t-Ca (mmol/L) (2.35±0.13) mmol/L, (2.35±0.12) mmol/L, (2.35±0.15) mmol/L, (2.26± 0.18) mmol/L, (2.07±0.29) mmol/L and (2.31±0.26) mmol/L; iPTH: 57.8(45.6, 91.8) ng/L, 54.1(37.8, 74.6) ng/L, 71.6(45.8, 102.2) ng/L, 131.1(81.7, 205.1) ng/L, 277.5(173.6, 395.3) ng/L and 354.9 (194.4, 720.3) ng/L; The stepwise logistic regression analysis showed: hypocalcemia (OR=3.32, P＜0.01) and decreased GFR (OR=5.28, P＜0.01) were independent risk factors of iPTH elevation at stage CKD3～5. Conclusions From the beginning of the CKD3 stage, serum t - Ca, P, iPTH level began to be relatively abnormal as renal function declined. Hyperphosphatemia, SHPT has not been improved significantly in CKD5D stage patients even with hemodialysis. The regulation of hemodialysis on serum calcium showed "overcorrecting" phenomenon.