Nephropathy in Patients with Cyanotic Congenital Heart Disease

Older pediatric patients with cyanotic congenital heart disease (CCHD) often develop nephropathy. Although felt to be secondary to glomerular dysfunction, there have been only a few papers examining renal tubular abnormalities in such patients. We therefore evaluated renal function in 16 patients with CCHD aged 3 to 28 years. The six oldest patients (aged 15 to 28 years), had documented proteinuria and low creatinine clearance levels. The urinary concentration of microalbumin was increased when compared to control values in 7 of the 16 patients; six of the patients had proteinuria while one did not. Urinary levels of N-acetyl-beta-D-glucosaminidase (NAG) were elevated in 14 patients including those without proteinuria. Concentrations of blood urea nitrogen and creatinine as well as serum and urinary concentrations of beta 2-microglobulin levels were elevated in certain patients. The serum concentration of uric acid was notably greater in all CCHD patients relative to controls. Furthermore, serum uric acid concentrations and urinary microalbumin levels correlated with patient age. In conclusion, renal tubular dysfunction as well as glomerular dysfunction occur in patients with CCHD. Urinary NAG may be useful as an early marker for the early detection of tubular dysfunction, while urinary microalbumin levels are useful in assessing glomerular dysfunction in these patients.