IgG4-Related Tubulointerstitial Nephritis Complicating the Course of Chronic Kidney Disease

An 82-year old hadfor > 20 years chronic kidney disease (CKD) attributed to hypertensive nephrosclerosis. Proteinuria and abnormalities of the urine sediment had been consistently absent and the rise in serum creatinine had been slow, with levels < 1.80 mg/dL for several years. Then, serum creatinine rose to a peak of 2.83 mg/dL within three months, while urine findings remained unchanged and there were no clinical manifestations from other organs. Ultrasonographic study of the kidneys and urinary bladder was normal and volume replacement did not halt the progressive rise in serum creatinine. Serum IgG4 level was elevated and serum complement levels (both C3 and C4) were markedly depressed. Percutaneous kidney biopsy revealed both IgG4-related tubulointerstitial nephritis (TIN) and advanced chronic arterial and arteriolar sclerosis. Treatment with oral prednisone led to rapid improvement of serum creatinine concentrations, which returned to 1.80 mg/dL in one month, and of serologies with decrease in serum IgG4 concentration and sustained normalization of the serum complement levels. Development of IgG4-related TIN without radiographic or urinary changes in patients with preexisting CKD who had benign urinary sediment and no proteinuria, urinary tract obstruction, circulatory dysfunction or ingestion of nephrotoxic agents may lead to rapid deterioration of the renal function. In these patients, timely diagnosis guided by kidney biopsy leads to appropriate treatment which may reverse the rapid deterioration of the renal function.