Sandle L N, Braganza J M
Clin Chim Acta. 1987 Feb 15;162(3):245-56. doi: 10.1016/0009-8981(87)90044-1.
We have evaluated a low-pH enzymatic method for measuring urinary D-glucaric acid, and its usefulness as a marker of 'enzyme induction' in patients with exocrine pancreatic disease. The coefficient of variation lay between 7.5 and 10.9% for within-batch precision, and between 7.9 and 19.8% for between-batch precision. The useful range of the method was 20-200 mumol/l, with a lower detection limit of 11 mumol/l. The molar concentration ratio of D-glucaric acid to creatinine in urine correlated with the 8-h output of D-glucaric acid (p less than 0.005): both indices were significantly higher in a group of 29 patients with exocrine pancreatic disease than in controls (median ratios 4.6 and 2.9 X 10(-3), p less than 0.005; median outputs 14.0 and 8.8 mumol/8 h, respectively, p less than 0.005). Comparison with the results of theophylline tests in the same group of patients showed that whereas 72% of patients had theophylline clearances higher than the highest value in controls, 45% of the group had increased D-glucaric acid/creatinine ratios, whilst only 21% had increased outputs of D-glucaric acid. Paradoxically, in patients with established liver disease in whom drug metabolism was impaired urinary D-glucaric acid values were amongst the highest encountered in the study. Thus, the obvious advantages of the method--non-invasive, simple, reproducible, inexpensive, easily applied to out-patients--are offset by an unacceptably low predictive value as an indicator of microsomal 'enzyme induction'.
我们评估了一种用于测量尿中D - 葡糖二酸的低pH酶法，以及该方法作为外分泌性胰腺疾病患者“酶诱导”标志物的效用。批内精密度的变异系数在7.5%至10.9%之间，批间精密度的变异系数在7.9%至19.8%之间。该方法的有效范围是20 - 200μmol/L，检测下限为11μmol/L。尿中D - 葡糖二酸与肌酐的摩尔浓度比与D - 葡糖二酸的8小时排出量相关（p < 0.005）：在一组29例外分泌性胰腺疾病患者中，这两个指标均显著高于对照组（中位数比值分别为4.6和2.9×10⁻³，p < 0.005；中位数排出量分别为14.0和8.8μmol/8小时，p < 0.005）。与同一组患者的茶碱试验结果比较显示，虽然72%的患者茶碱清除率高于对照组的最高值，但该组45%的患者D - 葡糖二酸/肌酐比值升高，而只有21%的患者D - 葡糖二酸排出量增加。矛盾的是，在药物代谢受损的已确诊肝病患者中，尿中D - 葡糖二酸值是该研究中所遇到的最高值之一。因此，该方法具有非侵入性、简单、可重复、廉价、易于应用于门诊患者等明显优点，但作为微粒体“酶诱导”指标的预测价值低得令人无法接受，这抵消了这些优点。
