Department of Urology, Indiana University School of Medicine, United States; Center for Pediatric and Adolescent Comparative Effectiveness Research, United States.
Department of Biostatistics, Indiana University School of Medicine and Richard M. Fairbanks School of Public Health, Indianapolis, IN, United States.
J Pediatr Urol. 2019 Feb;15(1):74.e1-74.e7. doi: 10.1016/j.jpurol.2018.10.019. Epub 2018 Oct 28.
Approximately half of adult stone formers submit specimens that are either under or over collections as determined by 24-h creatinine/kg. Previously identified predictors of inadequate collection in adults include female sex, older age, higher body mass index (BMI), vitamin D supplementation, and weekday collection.
The objective of this study is to determine risk factors for inadequate 24-h urinary specimen collection in the pediatric population.
A retrospective analysis of all children (<18 years of age) with renal and/or ureteral calculi evaluated at the study tertiary care pediatric center from 2005 to 2015 was performed. Those who had at least one 24-h urinary metabolic profile after a clinical visit for kidney and/or ureteral stones were included; children with bladder stones were excluded. Adequate collections had a urine creatinine of 10-15 mg/kg/24 h. A bivariate analysis of potential factors associated with inadequate collection of the initial urinary metabolic profile, including child demographics, parental socio-economic factors, history of stone surgery, and weekday vs. weekend urine collection, was performed. A mixed-effects logistic regression, controlling for correlation of specimens from the same patient, was also performed to determine whether an initial inadequate collection predicted a subsequent inadequate collection.
Of 367 patients, 80 had an adequate collection (21.9%): median age, 13 years (interquartile range, 8-16); 61.1% female; 93.5% white; 19.5% obese; and 13.0% overweight. No parental or child factors were associated with inadequate collection (Summary Table). Of inadequate collections, more than 80% were over collections. In the 175 patients with more than one 24-h urinary specimen collection, the effect of an initial inadequate collection on subsequent inadequate collections was not significant after controlling for the correlation of samples from the same patient (p = 0.8).
Any parental or child factors associated with the collection of inadequate 24-h urine specimens in children were not found. An initial inadequate collection does not predict subsequent inadequate collections. It was surprising that >80% of the inadequate collections were over collections rather than under collections. Possible explanations are that children collected urine samples for longer than the 24-h period or that stone-forming children produce more creatinine per 24-h period than healthy children due to hyperfiltration.
Inadequate collections are very common, and the risk factors for them are unclear. A repeat collection would be suggested if the first is inadequate. Further studies must be planned to explore barriers to accurate specimen collection using qualitative research methodology.
大约有一半的成年结石患者提交的标本要么低于，要么高于 24 小时肌酐/公斤所确定的采集量。先前确定的成人采集量不足的预测因素包括女性、年龄较大、较高的体重指数（BMI）、维生素 D 补充剂和在工作日采集。
本研究旨在确定儿科人群中 24 小时尿液标本采集不足的危险因素。
对 2005 年至 2015 年在研究三级儿科中心就诊的所有患有肾和/或输尿管结石的儿童（<18 岁）进行回顾性分析。将至少有一次 24 小时尿液代谢谱检查的患者纳入研究，这些患者在临床就诊后进行了肾和/或输尿管结石检查；将膀胱结石患者排除在外。充分采集的尿液肌酐为 10-15mg/kg/24h。对可能与初始尿液代谢谱采集不足相关的因素（包括儿童人口统计学、父母社会经济因素、结石手术史、以及工作日与周末尿液采集）进行了双变量分析。还进行了混合效应逻辑回归分析，控制了同一患者标本的相关性，以确定初始采集不足是否预测后续采集不足。
在 367 名患者中，80 名患者采集的标本充分（21.9%）：中位年龄 13 岁（四分位距 8-16）；61.1%为女性；93.5%为白人；19.5%肥胖；13.0%超重。未发现父母或儿童因素与采集不足有关（总结表）。在采集不足的患者中，超过 80%的患者为采集量过多。在 175 名有超过一次 24 小时尿液标本采集的患者中，在控制同一患者样本相关性后，初始采集不足对后续采集不足的影响不显著（p=0.8）。
未发现任何与儿童采集 24 小时尿液标本不足相关的父母或儿童因素。初始采集不足不能预测后续采集不足。令人惊讶的是，>80%的采集不足标本是采集过多，而不是采集过少。可能的解释是，儿童的尿液采集时间超过了 24 小时，或者由于超滤，结石形成的儿童每 24 小时产生的肌酐量高于健康儿童。
采集不足非常常见，但风险因素尚不清楚。如果第一次采集不足，建议进行再次采集。必须计划进行进一步的研究，使用定性研究方法探讨准确采集标本的障碍。
