Effectiveness of the Additional Administration of Spironolactone on Hypoproteinemia after the Fontan Procedure

We report a patient who showed dramatic improvement in his condition after additional administration of spironolactone for hypoproteinemia following the Fontan procedure. The patient was a 3-year-old boy with a univentricular heart and coarctation of the aorta. After the Fontan procedure, he was administered torasemide and tadalafil to maintain his circulatory status. He attended our hospital because of vomiting and intermittent abdominal pain 6 months after the procedure, and hypoproteinemia (serum protein, 4.3 g/dL, serum albumin, 2.5 g/dL and IgG, 182 mg/dL) was observed. Because proteinuria was not detected, we speculated that the patient was in the initial phase of protein-losing enteropathy (PLE) based on his previous medical history. He was ini-tially administered immunoglobulin and tolvaptan, an antidiuretic hormone receptor blocker, and was followed up by periodical supplementation of immunoglobulin. However, 3 months after the treatment, no improvement was observed in his condition and his serum protein, albumin, and immunoglobulin levels did not recovered to normal levels. We therefore added spironolactone to his therapy, which resulted in a dramatic improvement in his hypoproteinemia without any adverse effects. The patient ʼ s condition has remained stable since then. This case shows that the administration of spironolactone is a therapeutic choice for PLE in patients who undergo the Fontan procedure.