In the early stages of the disease, many patients have no obvious symptoms and are unaware of any problems. In these patients, IgA nephropathy may be suspected only during routine screening or investigation of another condition. However, some patients may present with aggressive disease.
In general, there are few characteristic clinical signs; however, microscopic hematuria and proteinuria may be persistently or intermittently detected for many years. It is important that patients undergo further investigations at an early stage, despite the tendency of many physicians not to act until renal function is severely impaired. A definitive diagnosis of IgA nephropathy can be made only by renal biopsy and immunohistologic examination. Up to 20 percent of patients with IgA nephropathy present with severe azotemia that represents long-standing disease that differs from the classic presentations, either because the patient's condition did not come to early medical attention or because the patient was referred late without an established diagnosis.
The decision by a nephrologist to recommend renal biopsy in a patient without symptoms who has microscopic hematuria and mild proteinuria varies from region to region and remains a matter of debate even when IgA nephropathy is highly suspected. This relates in part to the lack of effective treatment in the early stages of the disease and the realization that none may be necessary. Moreover, although some mild cases progress to renal failure, there are no consistent genetic, immunologic, clinical, or morphologic markers that predict progressive disease in a patient without symptoms who has minor urinary abnormalities.
