The nephropathy of type I tyrosinemia after liver transplantation

Type I tyrosinemia (HTI) is an autosomally recessively inherited disease caused by deficiency of fumarylacetoacetate hydrolase. The disease manifests with liver failure, renal tubular defects, and neurologic crises. Currently orthotopic liver transplantation (OLT) enables patients to survive. However, renal fumarylacetoacetate hydrolase deficiency is not corrected by OLT, and the long-term prognosis of the nephropathy is not known. We investigated tyrosine metabolism, GFR, renal tubular function, and histopathology before and 18-36 mo after OLT in eight patients with HTI. Progressive renal dysfunction was not documented despite continuing, although diminished, urinary succinylacetone excretion in all patients. The mean GFR was 82 mL/min/1.73 m2 before and 102 mL at 18 mo and 93 mL at 36 mo after OLT. All patients showed tubular dysfunction before OLT. At 18 mo, glucosuria occurred in one, amino aciduria and phosphaturia in three, and hypercalciuria in six patients. Only hypercalciuria was seen at 36 mo. Renal biopsies showed mild nonspecific changes caused either by minimal progression of the renal disease or by mild cyclosporine nephrotoxicity. In conclusion, patients with HTI had normal GFR, but showed signs of tubular dysfunction 18-36 mo after OLT. Renal function and histopathology should be monitored after OLT for HTI.