Occupational and Environmental Medicine, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg & Sahlgrenska University Hospital, Sweden.
National Institute of Occupational Health, Oslo, Norway.
Environ Res. 2022 Sep;212(Pt C):113412. doi: 10.1016/j.envres.2022.113412. Epub 2022 May 4.
Lead is a non-essential toxic trace element. Lead in blood (BPb) is the most common biomarker of lead exposure but lead in urine (UPb) has also been used. There is, however, limited data on the variability of UPb in the general population and the association with BPb.
Our aims were to assess variability of lead in repeated blood and urine samples. The diurnal variation of UPb was also examined as well as associations with BPb.
We established an openly available biobank including 60 healthy non-smoking individuals, 29 men and 31 women, 21-64 years of age (median 31 years), with repeated sampling of blood and urine. Timed urine samples were collected at six fixed time points in two 24 h periods, about one week apart, and adjusted for creatinine and specific gravity (SG). BPb and UPb were analyzed by inductively coupled plasma mass spectrometry. The within- and between-individual variabilities and intra-class correlation coefficients (ICCs; ratios of the between-individual to total observed variances) were calculated using mixed-effects models.
The ICCs for UPb samples were mostly above 0.5, when adjusted for creatinine or SG, and higher for overnight samples compared with daytime samples. The highest ICCs were obtained for BPb (ICC = 0.97) and for urine samples corrected for dilution by SG or creatinine. The ICC was 0.66 for overnight samples adjusted for creatinine. High correlations with BPb were found for 24 h UPb (r = 0.77) and overnight samples, e.g. r = 0.74 when adjusted for SG. There was diurnal variation of UPb with lowest excretion rate in overnight samples. There was also a significant association between the Pb excretion rate and urinary flow rate.
In addition to BPb, UPb adjusted for creatinine or SG seems to be a useful biomarker for exposure assessment in epidemiological studies.
铅是非必需的有毒微量元素。血铅（BPb）是最常见的铅暴露生物标志物，但尿铅（UPb）也被使用。然而，关于普通人群中 UPb 的变异性以及与 BPb 的关联的数据有限。
我们的目的是评估重复血样和尿样中铅的变异性。还检查了 UPb 的昼夜变化以及与 BPb 的关联。
我们建立了一个公开的生物银行，包括 60 名健康不吸烟的个体，29 名男性和 31 名女性，年龄 21-64 岁（中位数 31 岁），每隔一周左右重复采集血样和尿样。在两个 24 小时期间的六个固定时间点采集定时尿液样本，并根据肌酐和比重（SG）进行调整。采用电感耦合等离子体质谱法分析 BPb 和 UPb。使用混合效应模型计算 UPb 样本的个体内和个体间变异性以及组内相关系数（ICC；个体间方差与总观察方差的比值）。
调整肌酐或 SG 后，UPb 样本的 ICC 大多高于 0.5，且夜间样本的 ICC 高于日间样本。BPb（ICC=0.97）和通过 SG 或肌酐校正稀释的尿液样本的 ICC 最高。调整肌酐后，夜间样本的 ICC 为 0.66。24 小时 UPb（r=0.77）与 BPb 高度相关，例如，调整 SG 后 r=0.74。UPb 存在昼夜变化，夜间样本的排泄率最低。尿铅排泄率与尿流率之间也存在显著关联。
除了 BPb 外，通过肌酐或 SG 调整的 UPb 似乎是评估流行病学研究中暴露的有用生物标志物。
