Department of Clinical Chemistry, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium.
Clin Biochem. 2013 Dec;46(18):1825-9. doi: 10.1016/j.clinbiochem.2013.08.021. Epub 2013 Sep 9.
The quantification of total urinary porphyrins based on spectrophotometry or spectrofluorimetry is a key screening test in cutaneous or mixed porphyria, performed before the quantitative fractionation of porphyrin isomers by chromatography. The aim of the present study was to determine the best threshold value for a spectrophotometric screening test and to estimate its diagnostic performances.
Data from samples sent to the laboratory between January 2006 and July 2013 from patients with a suspicion of cutaneous or mixed porphyria were retrospectively collected. The final diagnosis was based on the clinical presentation and biochemical results performed on appropriate specimens. Control samples were obtained from 91 non-porphyria patients and 58 healthy individuals and patient samples were obtained from 38 patients with symptomatic porphyria. The sensitivity and specificity of the spectrophotometric screening test were calculated at different cutoff values expressed in nmol/L and nmol/mmol creatinine using receiver operator curves.
A threshold of 18.8nmol/mmol creatinine was considered as the best cutoff value for the screening test, achieving a sensitivity of 100% and a specificity of 93.2%.
分光光度法或荧光分光光度法测定总尿卟啉的定量分析是皮肤卟啉症或混合性卟啉症的关键筛选试验，该检测应在色谱法定量分离卟啉异构体之前进行。本研究旨在确定分光光度筛选试验的最佳阈值，并评估其诊断性能。
回顾性收集了 2006 年 1 月至 2013 年 7 月期间因疑似皮肤或混合性卟啉症而送往实验室的样本数据。最终诊断基于临床表现和对适当标本进行的生化结果。对照组样本来自 91 名非卟啉症患者和 58 名健康个体，患者组样本来自 38 名有症状性卟啉症患者。使用接收者操作特征曲线，计算不同截值（以 nmol/L 和 nmol/mmol 肌酐表示）下分光光度筛选试验的灵敏度和特异性。
以 18.8 nmol/mmol 肌酐作为筛选试验的最佳截值，此时的灵敏度为 100%，特异性为 93.2%。
