A 3-year-old boy with congenital absence of the portal vein presenting fasting hypoglycemia and postprandial hyperglycemia with hyperinsulinemia

Abstract A 3-year-old boy developed hypoglycemia with convulsions, rectal bleeding and hyperammonemia. Three-dimensional computed tomography scanning revealed the missing main branch of the portal vein, which confirmed the diagnosis of congenital absence of the portal vein (CAPV). Oral glucose tolerance test showed hyperglycemia with hyperinsulinemia at 30 min, whereas hypoglycemia was observed during fasting and at 120 min. Postprandial hyperglycemia was observed repeatedly. Repetitive hypoglycemia and rectal bleeding were uncontrollable. Living-donor liver transplantation, which was successfully performed, was apparently effective in preventing fasting hypoglycemia and improving hyperammonemia; rectal bleeding ceased after the surgery. Considerably, CAPV could result in hyperinsulinemia with partial failure of hepatic insulin degradation and hypoglycemia due to the lack of glycogen accumulation. Postprandial hyperglycemia could result from the fact that glucose-abundant splanchnic blood directly flows into the systemic circulation through the portosystemic shunt. Therefore, it is important to be aware of CAPV as a cause of glucose metabolism abnormalities including fasting hypoglycemia and postprandial hyperglycemia with hyperinsulinemia.