[IgA nephropathy: frequent, but rarely diagnosed].

IgA nephropathy (IgAN) is the most common type of glomerulonephritis in the western world. In the majority of cases, it manifests in adolescence or early adulthood as recurrent macrohematuria, frequently triggered by infections, or persistent microhematuria as well as mild proteinuria, hypertension and/or renal insufficiency. In view of the later, it is not surprising that IgAN is often a chance finding. The majority of affected persons probably never come to medical attention, since in autopsies a prevalence of up to 1% of the population has been reported. About 20-30% of patients with a diagnosis of IgAN suffer from chronic, slowly progressive renal failure. Predictors include the degree of proteinuria and arterial hypertension as well as the established renal impairment at the time of diagnosis. Early identification of this risk group is of particular importance, since adequate therapy can stop or at least retard the progression of renal failure. When end stage renal failure has developed and a renal transplant is performed, about 25% of the patients will experience a clinically relevant recurrence of IgAN with progressive graft dysfunction.