慢性肾脏病3～5期透析前患者矿物质及骨代谢紊乱的调查分析

Investigation of mineral and bone metabolic disorders in pre-dialysis patients with chronic kidney disease at stage 3 to 5

目的 调查慢性肾脏病(chronic kidney disease,CKD)透析前患者的钙磷代谢及甲状旁腺激素状况,为非透析CKD患者矿物质及骨代谢紊乱的诊治提供依据。方法 按照CKD分期,比较155名CKD3-5期透析前患者的血钙、血磷、全段甲状旁腺素(intact parathyroid hormone,iPTH)及碱性磷酸酶(alkaline phosphatase,AKP)的水平,评估继发性甲状旁腺功能亢进症(secondary hyperparathyroidism,SHPT)的发生率,并对各项指标进行相关性分析。结果 在CKD3～5期,患者血钙(mg/dl)分别为8.62±0.69、8.48±1.31和7.69±1.25,血磷(mg/dl)分别为4.37±1.33、5.50±1.57和7.59±2.41,钙磷乘积(mg2/dl2)分别为37.64±11.09、47.13±14.17和60.53±21.87,AKP(U/L)分别为146.62±130.56、125.33±92.31和131.76±68.85,iPTH(pg/ml)分别为155.77±198.95、353.6±381.93和434.37±351.03。低钙血症的发生率分别为22.2%、29.4%和68.3%,高磷血症的发生率分别为15.6%、56.8%和76%,SHPT的发生率分别为47.6%、56.8%和80.4%。比较显示,CKD3期和CKD4期患者的血钙水平无显著性差异(P>0.05);CKD5期患者的血钙水平显著低于CKD3期(P<0.01)和CKD4期(P<0.05),各期患者的血磷、钙磷乘积及iPTH水平均随疾病的进展而显著升高(P<0.01,P<0.001),AKP水平无统计学差异(P>0.05),CKD5期患者低钙血症的发生率显著高于CKD3期和CKD4期(P<0.001),各期患者高磷血症和SHPT的发生率均随疾病的进展而显著提高(P<0.001)。以iPTH为因变量,血钙、血磷、钙磷乘积、AKP和GFR为自变量进行相关分析,结果显示,iPTH水平与血磷(r=0.526,P<0.01)、钙磷乘积(r=0.483,P<0.01)成正相关;与GFR(r=-0.552,P<0.01)、校正钙(r=-0.405,P<0.01)成负相关;与AKP无相关性。在此基础上,以iPTH为因变量,年龄、性别、血钙、血磷、钙磷乘积、GFR为自变量,进行多元回归分析,结果显示,血钙、血磷、GFR进入回归方程,复相关系数R=0.576,是iPTH独立影响因素(P<0.05)。结论 CKD患者的钙磷代谢紊乱在疾病的早期即存在,且随疾病的进展而恶化,应重视早期干预,从而改善预后。

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.