Loun B, Copeland K R, Sedor F A
Department of Pathology, Division of Clinical Laboratories, Duke University Medical Center, Durham, NC 27710, USA.
Clin Chem. 1996 Jun;42(6 Pt 1):965-9.
We investigated the efficiency, accuracy, and reliability of the ultrafiltration/dipstick methodology commonly used to diagnose myoglobinuria. Twenty-five myoglobin-containing urine specimens were filtered by centrifugation for 15 min at 1500g through a Centricon-30 membrane filter. Both the original specimen and filtrate were assayed for myoglobin. The amount of myoglobin recovered subsequent to filtration varied from <1-38%. This poor and variable recovery was independent of sample matrix or precentrifugation of the specimens. This was most critical for urine specimens with myoglobin concentrations <60 000 microg/L. Fourteen of 18 such filtrates had concentrations <350 microg/L, a concentration below which a negative result would be obtained by using conventional dipstick methods. Thus, the use of this procedure has the potential to misdiagnose patients with myoglobin concentrations associated with increased risk of subsequent renal dysfunction, in particular when urine myoglobin concentrations are <60 000 microg/L.
我们研究了常用于诊断肌红蛋白尿的超滤/试纸条法的效率、准确性和可靠性。将25份含肌红蛋白的尿液标本在1500g条件下通过Centricon - 30膜过滤器离心15分钟进行过滤。对原始标本和滤液都进行了肌红蛋白检测。过滤后回收的肌红蛋白量在<1%至38%之间变化。这种回收率低且变化不定与样品基质或标本的预离心无关。对于肌红蛋白浓度<60000μg/L的尿液标本，这一点最为关键。18份此类滤液中有14份的浓度<350μg/L，而使用传统试纸条法在此浓度以下会得出阴性结果。因此，使用该程序有可能对肌红蛋白浓度与后续肾功能障碍风险增加相关的患者进行误诊，尤其是当尿液肌红蛋白浓度<60000μg/L时。
