Abstract
INTRODUCTION: Protein losing enteropathy (PLE) is usually a diagnosis of exclusion, which requires cumbersome tests to confirm. In the quest for a simpler diagnostic test, we hypothesized that a spot stool sample estimation of α-1 antitrypsin will be sufficient to make a diagnosis of PLE, if we control for serum α-1 antitrypsin concentration and degree of stool dilution. MATERIALS AND METHODS: Consecutive patients with a clinical suspicion of PLE and who had been advised a scintigraphy study were recruited after getting informed consent. The study excluded patients less than 1 year of age, pregnant women, and those with a clinical suspicion of chronic pancreatitis. Serum α-1 antitrypsin, spot stool α-1 antitrypsin, and stool elastase was assessed in all the patients. The diagnostic value of the index test was estimated from the patients with positive scintigraphy scan compared with a negative scan, expressed as sensitivity and specificity and the area under the receiver operating characteristic curve (AUROC). RESULT: A total of 33 patients underwent scintigraphy with a clinical suspicion of PLE. Twenty patients (60%) showed tracer activity in the gut suggestive of PLE. Spot stool α-1 antitrypsin below 0.26 mg/g had a sensitivity of 100% to rule out PLE; however, the specificity was only 46%. Spot stool α-1 antitrypsin/(serum α-1 antitrypsin * elastase) ratio performed similar to spot stool α-1 antitrypsin as a diagnostic test (AUROC: 0.814 [0.61-1.0] vs. 0.796 [0.54-1.0]). CONCLUSION: Random stool antitrypsin is a sensitive test for diagnosing PLE; however, it lacks specificity. Spot stool α-1 antitrypsin/(serum α-1 antitrypsin * stool elastase) does not provide any additional value in the diagnosis of this syndrome.