Renal (kidney) involvement is common, occurring in 30-70 % of patients. Kidney disease is usually noted after the onset of systemic symptoms. More marked findings may also occur including nephrotic syndrome, a situation characterized by abnormal excretion of proteins and lipids in urine, swelling (edema), low level of albumin in blood and hyperlipidemia. High blood pressure (hypertension) and acute kidney failure may also be seen. Worsening of the kidney symptoms and biopsy-confirmed worsening of the kidney lesions may be observed in patients with repeated attacks of rash or hematuria (blood in the urine).