BackgroundLittle is known about the enteric protein loss in patients after a modified Fontan operation before the appearance of overt symptoms or signs of protein-losing enteropathy (PLE). The authors examined the possibility of using fecal &agr;1-antitrypsin concentration measurements for the early detection of postoperative PLE and in longer term postoperative monitoring of these patients.MethodsThe authors compared fecal &agr;1-antitrypsin concentrations in stool samples from 12 children 12.0 to 43.7 months after modified Fontan operations with those of 12 age-matched control subjects and examined the relationship between the &agr;1-antitrypsin levels and time since operation. The authors also compared fecal &agr;1-antitrypsin concentrations of stools from the same patients obtained at two different time points after surgery with intervals between samples ranging from 14.7 to 19.8 months.ResultsNo significant differences in serum total protein and albumin levels were observed between patients after the modified Fontan operation and control subjects. The fecal concentrations of &agr;1-antitrypsin in patients after the Fontan operation were significantly (P< 0.01) higher than those in control subjects. There was no significant correlation between fecal &agr;1-antitrypsin concentrations and time elapsed after the Fontan operation. The fecal &agr;1-antitrypsin concentration increased significantly (P< 0.01) over periods of 14.7 to 19.8 months after the first measurement.ConclusionThe results show that enteric protein loss begins before the appearance of hypoproteinemia in patients after a modified Fontan operation, and that the measurement of fecal &agr;1-antitrypsin concentrations in random stool samples is useful as an early indicator. To watch for the development of PLE after Fontan operation, it may be important to perform longitudinal follow-up examinations of enteric protein loss by measuring fecal &agr;1-antitrypsin concentrations early in the postoperative period.