Department of Internal Medicine, Viborg Regional Hospital, Viborg, Denmark.
Scand J Clin Lab Invest. 2009;69(8):831-6. doi: 10.3109/00365510903307947.
To evaluate the day-to-day biological variation of cystatin C in comparison with creatinine in healthy subjects and in patients with impaired renal function.
Eight weekly morning blood samples were taken from 20 healthy subjects (13 females and 7 males, median age 44 years, range 25-61) and 19 patients with impaired renal function (8 females and 11 males, median age 61 years, range 35-70). Serum cystatin C was measured using Dade Behring N Latex Cystatin C assay and serum creatinine by an enzymatic method (Roche).
In the healthy subjects mean serum cystatin C was 0.70 mg/L (range 0.44-1.09) and mean serum creatinine 77 micromol/L (range 54-100). The analytical variance was 2.0% for cystatin C and 1.6% for creatinine. The intra-individual variance was greater for cystatin C than for creatinine (8.6% vs. 4.7%). The inter-individual variance was similar for both analytes (cystatin C 15.1% vs. creatinine 14.4%). In the patients with impaired renal function mean serum cystatin C was 1.86 mg/L (range 0.45-3.31) and mean serum creatinine 224 micromol/L (range 103-430). The analytical variance was 1.8% for cystatin C and 1.4% for creatinine. The intra-individual variance was greater for cystatin C than for creatinine (16.0% vs. 8.9%).
In the present study, the intra-individual variance was greater for cystatin C than for creatinine in both healthy subjects and in patients with impaired renal function. Accordingly, serum creatinine is the preferred marker for serial monitoring of renal function in individuals with stable muscle mass.
评估胱抑素 C 与肌酐在健康受试者和肾功能受损患者中的日常生物学变异。
从 20 名健康受试者（13 名女性和 7 名男性，中位年龄 44 岁，范围 25-61 岁）和 19 名肾功能受损患者（8 名女性和 11 名男性，中位年龄 61 岁，范围 35-70 岁）中每周采集 8 份早晨血样。使用 Dade Behring N Latex Cystatin C 测定法测定血清胱抑素 C，用酶法（罗氏）测定血清肌酐。
在健康受试者中，血清胱抑素 C 的平均值为 0.70mg/L（范围 0.44-1.09），血清肌酐的平均值为 77μmol/L（范围 54-100）。胱抑素 C 的分析变异为 2.0%，肌酐的分析变异为 1.6%。胱抑素 C 的个体内变异大于肌酐（8.6%比 4.7%）。两种分析物的个体间变异相似（胱抑素 C 为 15.1%，肌酐为 14.4%）。在肾功能受损的患者中，血清胱抑素 C 的平均值为 1.86mg/L（范围 0.45-3.31），血清肌酐的平均值为 224μmol/L（范围 103-430）。胱抑素 C 的分析变异为 1.8%，肌酐的分析变异为 1.4%。胱抑素 C 的个体内变异大于肌酐（16.0%比 8.9%）。
在本研究中，胱抑素 C 在健康受试者和肾功能受损患者中的个体内变异均大于肌酐。因此，在肌肉质量稳定的个体中，血清肌酐是肾功能连续监测的首选标志物。
