Urine biochemical markers of early renal dysfunction are associated with iron overload in beta-thalassaemia

Renal dysfunction in thalassemia patients can be attributed to chronic anemia, and iron overload as well as to desferioxamine (DFO) toxicity. We analyzed the urine of 91 well-maintained homozygous beta-thalassemia patients, with no evidence of renal disease, for early evidence of kidney dysfunction by means of electrophoresis and quantitative biochemical tests. Measurement of liver magnetic resonance imaging (MRI) T2 values and serum ferritin concentration was used to estimate iron overload. In 55 of the 91 patients, urine analysis indicated signs of tubular dysfunction. The urine concentration of albumin and beta 2-microglobulin, as well as the activity of N-acetyl-beta-D-glucosaminidase (NAG), correlated positively with serum ferritin concentration and liver iron deposition, as detected by MRI T2 values. This suggested that the cause of renal dysfunction in homozygous beta-thalassemia is iron overload. On the other hand, the same urine markers did not correlate with age, indicating that chronic anemia or desferrioxamine (DFO) treatment are not related to renal dysfunction in thalassemia.