随机尿钙/渗透压在评估肌肉量减少儿童的尿钙排泄中的应用

Random urine calcium/osmolality in the assessment of calciuria in children with decreased muscle mass.

作者信息

Richmond W, Colgan G, Simon S, Stuart-Hilgenfeld M, Wilson N, Alon U S

机构信息

Section of Nephrology, Children's Mercy Hospital, University of Missouri, Kansas City, MO 64108, USA.

出版信息

Clin Nephrol. 2005 Oct;64(4):264-70. doi: 10.5414/cnp64264.

DOI:10.5414/cnp64264

PMID:16240897

Abstract

BACKGROUND

Random urine Ca/creatinine (UCa/Cr) is used to estimate 24-hour Ca excretion. However, due to decreased urine creatinine excretion in children with decreased muscle mass (DMM), UCa/Cr overestimates their Ca excretion.

OBJECTIVE

To evaluate whether in children with DMM random urine Ca/osmolality (UCa/Osm) can accurately predict hypercalciuria (24-hour urine Ca > 4.0 mg/kg) and at which "cutoff" value.

METHODS

19 children with DMM and 29 with normal muscle mass (NMM), ages 6 - 17 years, were studied. DMM was diagnosed based on clinical findings and decreased serum creatinine, and confirmed by low urine creatinine excretion. Over 24 hours, subjects collected each void separately. After each sample was analyzed, samples of each participant were combined to form a 24-hour specimen from which an aliquot (AL) was obtained; 24-hour urine Ca was first correlated with the corresponding AL Ca/Cr and Ca/Osm. As an internal control, a similar assessment ofproteinuria was conducted. In the next step, AL data were compared with individual urine samples to identify the time of day when a random sample best correlates with AL.

RESULTS

The correlation coefficient between 24-hour Ca and AL Ca/Cr in all children was 0.61, in NMM 0.96, and in DMM 0.69 (in all p < 0.001). The correlation coefficient between 24-hour urine Ca and AL Ca/Osm in all children was 0.90, in NMM 0.90, and in DMM 0.91 (in all p < 0.001). In children with DMM, the correlation coefficient of 24-hour protein with AL protein/Cr was 0.75, and with protein/Osm 0.98 (both p < 0.001). Receiver operating characteristic curves showed UCa/Cr as a better predictor of 24-hour Ca > 4.0 mg/kg in NMM, whereas UCa/Osm was a better predictor of hypercalciuria in DMM patients. In NMM, UCa/Cr ratio > 0.20 had sensitivity of 88% and specificity of 96% in detecting 24-hour Ca > 4.0 mg/kg, whereas in those with DMM UCa/Osm (x 10) ratio of > 0.25 had sensitivity of 100% and specificity of 93% in detecting hypercalciuria. It was further found that random urine specimens collected between 9:00 a.m. and 2:00 p.m. best represented 24-hour urine data.

CONCLUSION

In children with DMM, UCa/Osm can successfully replace UCa/Cr as a screening tool for hypercalciuria.

摘要

背景

随机尿钙/肌酐（UCa/Cr）用于估算24小时尿钙排泄量。然而，由于肌肉量减少（DMM）的儿童尿肌酐排泄减少，UCa/Cr会高估他们的钙排泄量。

目的

评估在DMM儿童中，随机尿钙/渗透压（UCa/Osm）能否准确预测高钙尿症（24小时尿钙>4.0mg/kg）以及在哪个“临界”值时可以预测。

方法

对19名6至17岁的DMM儿童和29名肌肉量正常（NMM）的儿童进行研究。根据临床表现和血清肌酐降低诊断DMM，并通过低尿肌酐排泄量进行确认。在24小时内，受试者分别收集每次排尿。对每个样本进行分析后，将每个参与者的样本合并形成一个24小时标本，从中获取一份等分试样（AL）；首先将24小时尿钙与相应的AL钙/肌酐和钙/渗透压进行相关性分析。作为内部对照，对蛋白尿进行了类似的评估。在下一步中，将AL数据与个体尿液样本进行比较，以确定随机样本与AL相关性最佳的一天中的时间。

结果

所有儿童中24小时钙与AL钙/肌酐之间的相关系数为0.61，NMM中为0.96，DMM中为0.69（所有p<0.001）。所有儿童中24小时尿钙与AL钙/渗透压之间的相关系数为0.90，NMM中为0.90，DMM中为0.91（所有p<0.001）。在DMM儿童中，24小时蛋白与AL蛋白/肌酐的相关系数为0.75，与蛋白/渗透压的相关系数为0.98（均p<0.001）。受试者工作特征曲线显示，UCa/Cr是NMM中24小时钙>4.0mg/kg的更好预测指标，而UCa/Osm是DMM患者高钙尿症的更好预测指标。在NMM中，UCa/Cr比值>0.20在检测24小时钙>4.0mg/kg时敏感性为88%，特异性为96%，而在DMM患者中，UCa/Osm（×10）比值>0.25在检测高钙尿症时敏感性为100%，特异性为93%。进一步发现，上午9:00至下午2:00之间收集的随机尿液标本最能代表24小时尿液数据。