A case of hydrothorax caused by peritoneal dialysate leakage diagnosed using the reaction between icodextrin and povidone-iodine

Hydrothorax occurs as a complication of peritoneal dialysis in about 2% of cases. When a pleural effusion occurs, the effusion should be analyzed as part of the differential diagnosis. A hydrothorax due to peritoneal dialysate leakage can be suspected based on higher glucose and lower protein content compared with serum. Computed tomography (CT) peritoneography, peritoneal scintigraphy, and magnetic resonance peritoneography are safe, accurate, and reliable methods for diagnosing hydrothorax. Here, we report a case of hydrothorax associated with dialysate leakage that could not be confirmed using standard CT peritoneography. We confirmed the leakage by observing the change in color to black in a test that involved adding povidone-iodine to the pleural fluid obtained by thoracentesis after a cycle of peritoneal dialysis with icodextrin solution. We propose using the icodextrin-povidone reaction as a test for hydrothorax caused by dialysate leakage.