Evaluation of Performance of Measurement of Faecal alpha(1)-Antitrypsin Clearance and Technetium-99m Human Serum Albumin Scintigraphy in Protein-Losing Enteropathy

Background and Aim: Our study aimed to compare the performance of faecal alpha(1)-antitrypsin clearance (AATC) and radio-labelled human serum albumin (HSA) scintigraphy in protein-losing enteropathy (PLE). Methods: Patients studied by both AATC and technetium-99m (Tc-99m)-labelled HSA scintigraphy were recruited and categorized into PLE and non-PLE groups based on clinical and laboratory findings. The performance of AATC and Tc-99m-labelled HSA scintigraphy was evaluated using clinical diagnosis of PLE as a gold standard. Results: 29 patients were recruited and 13 patients were considered to have definite PLE (PLE group). In the PLE group, all patients had a positive HSA scinigraphy and 10 (77%) had demonstrable positive tracing in the early phase. Conversely, only 6 of them (46%) had elevated AATC level (>13 m/day). Results of Tc-99m-labelled HSA scan (but not AATC) showed significant agreement with the clinical diagnosis (kappa 0.35, p = 0.013). Tc-99m-labelled HSA scintigraphy carried higher sensitivity (100 vs. 46%) and negative predictive value (100 vs. 63%) compared to AATC in diagnosing PLE. The correlation between the results of these two investigations was only modest (kappa 0.27, p = 0.04). The area under the receiver operating characteristic curve of AATC level showed no optimal diagnostic cut-off for PLE. Conclusion: Tc-99m-labelled HSA scintigraphy was superior to AATC in diagnosing PLE. Copyright (C) 2011 S. Karger AG, Basel