Ruaux Craig G, Steiner Jörg M, Williams David A
Gastrointestinal Laboratory, Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4474, USA.
Vet Clin Pathol. 2004;33(1):20-2. doi: 10.1111/j.1939-165x.2004.tb00344.x.
Measurement of proteolytic activity in feces is a traditional method for the diagnosis of exocrine pancreatic insufficiency (EPI). A drawback of this method is the occurrence of falsely low results that may lead to a false-positive diagnosis of EPI. We hypothesized that intestinal loss of serum proteinase inhibitors in protein-losing enteropathy (PLE) may inhibit fecal proteolytic activity and be a potential source of false low results.
The objective of this study was to determine the effect of PLE on fecal proteolytic activity in dogs.
Fecal proteolytic activity was measured using a radial diffusion casein digestion assay in 12 samples from 4 clinically healthy control dogs and 30 samples from 16 dogs with PLE. Gastrointestinal protein loss was assessed using an ELISA to determine fecal canine alpha 1-proteinase inhibitor concentration. The relationship between the concentration of canine alpha 1-proteinase inhibitor in the feces and the diameter cleared in the casein digestion assay was determined. The mean clearing diameter was compared between control dogs and dogs with PLE.
A significant negative correlation was observed between fecal canine alpha1-proteinase inhibitor concentration and casein clearing diameter (P <.001, Pearson r =.6317, r2 =.3999). Mean clearing diameter was significantly lower in dogs with PLE than in control dogs (12.63 vs 16.83 mm, P <.001, two-tailed Student's t-test).
Increased fecal loss of alpha1-proteinase inhibitor in dogs with PLE is associated with a significant decrease in fecal proteolytic activity and may result in a false positive diagnosis of EPI.
粪便中蛋白水解活性的测定是诊断外分泌性胰腺功能不全（EPI）的传统方法。该方法的一个缺点是会出现结果假性降低的情况，这可能导致EPI的假阳性诊断。我们推测，蛋白丢失性肠病（PLE）中血清蛋白酶抑制剂的肠道丢失可能会抑制粪便蛋白水解活性，并且是导致结果假性降低的潜在原因。
本研究的目的是确定PLE对犬粪便蛋白水解活性的影响。
采用放射状扩散酪蛋白消化试验，对4只临床健康对照犬的12份样本和16只患PLE犬的30份样本进行粪便蛋白水解活性测定。使用酶联免疫吸附测定法（ELISA）评估胃肠道蛋白丢失情况，以确定粪便中犬α1-蛋白酶抑制剂的浓度。确定粪便中犬α1-蛋白酶抑制剂浓度与酪蛋白消化试验中清除直径之间的关系。比较对照犬和患PLE犬的平均清除直径。
粪便中犬α1-蛋白酶抑制剂浓度与酪蛋白清除直径之间存在显著负相关（P <.001，Pearson相关系数r =.6317，r2 =.3999）。患PLE犬的平均清除直径显著低于对照犬（12.63对16.83 mm，P <.001，双侧Student t检验）。
患PLE犬粪便中α1-蛋白酶抑制剂的丢失增加与粪便蛋白水解活性显著降低有关，可能导致EPI假阳性诊断。
