Fagerstrom Peter, Sallsten Gerd, Akerstrom Magnus, Haraldsson Borje, Barregard Lars
Department of Occupational and Environmental Medicine, Sahlgrenska Academy, University of Gothenburg, PO Box 414, Gothenburg, S-405 30, Sweden.
Department of Molecular and Clinical Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
BMC Nephrol. 2015 Jan 24;16:8. doi: 10.1186/1471-2369-16-8.
Urinary albumin can be measured in 24 h or spot samples. The 24 h urinary albumin excretion rate is considered the gold standard, but is cumbersome to collect. Instead, often an overnight sample is collected, and adjusted for dilution. Proxies for 24 h excretion rate have been studied in diabetics, but seldom in healthy individuals. Our aims were to compare 24 h and overnight albumin excretion, to assess the impact of personal characteristics, and to examine correlations between the 24 h excretion rate and proxies such as the albumin to creatinine ratio (ACR).
Separate 24 h and overnight urine samples were collected from 152 healthy kidney donors. Urinary creatinine, specific gravity, collection time, and sample volume determined. Differences between 24 h and overnight samples were examined, and the effects of age, sex, smoking, body mass, glomerular filtration rate, and urinary flow rate were assessed.
The 24 h albumin excretion rate and ACR were both significantly higher than their overnight counterparts. Unadjusted albumin was unsurprisingly higher in the more concentrated overnight samples, while concentrations adjusted for specific gravity were similar. In multivariate analysis, the 24 h excretion rate and proxies were positively associated with glomerular filtration rate, as was ACR in overnight samples. There were positive associations between urinary albumin and body mass.
Proxies for the 24 h albumin excretion rate showed relatively high correlations with this gold standard, but differences due to sampling period, adjustment method, and personal characteristics were large enough to be worth considering in studies of albumin excretion in healthy individuals.
尿白蛋白可在24小时或随机尿样中进行检测。24小时尿白蛋白排泄率被视为金标准，但收集过程繁琐。因此，通常收集过夜尿样并进行稀释校正。虽然已对糖尿病患者的24小时排泄率替代指标进行了研究，但在健康个体中却很少见。我们的目的是比较24小时和过夜尿白蛋白排泄情况，评估个人特征的影响，并检验24小时排泄率与白蛋白肌酐比值（ACR）等替代指标之间的相关性。
从152名健康肾脏供体中分别收集24小时和过夜尿样。测定尿肌酐、比重、收集时间和样本量。检查24小时和过夜尿样之间的差异，并评估年龄、性别、吸烟、体重、肾小球滤过率和尿流率的影响。
24小时白蛋白排泄率和ACR均显著高于过夜尿样。不出所料，在浓缩程度更高的过夜尿样中，未经校正的白蛋白含量更高，而经比重校正后的浓度相似。在多变量分析中，24小时排泄率及其替代指标与肾小球滤过率呈正相关，过夜尿样中的ACR也是如此。尿白蛋白与体重之间存在正相关。
24小时白蛋白排泄率的替代指标与这一金标准显示出相对较高的相关性，但由于采样时间、校正方法和个人特征导致的差异足够大，在健康个体白蛋白排泄研究中值得考虑。
