Proteinuria in the prognosis of IgA nephropathy.

ABSTRACT

IgA Nephropathy (IgAN) is the most common lesion causing primary glomerulonephritis in the world. The main clinical predictors of progression are elevated blood pressure, high histological score and proteinuria. Although elevated serum creatinine concentration at diagnosis, increased excretion of cytochines, age at onset, obesity and genetic factors may all influence clinical outcome, it is quite clear that proteinuria is the hallmark of renal damage in IgAN. Patients with IgAN and little or no proteinuria (<500 mg/day) have low risk of progression in the short term, while the rate of decline in renal function is 25-fold faster in those with sustained proteinuria >3 g/day. The product of duration (years) and urinary protein excretion (g/day) at the time of renal biopsy is more significantly correlated with progression. So, this so called proteinuria index may be a useful predictor for glomerular and interstitial histopathological changes and the fate of renal function in IgAN. The progression of IgAN may be slowed by antihypertensive and antiproteinuric therapy, such as angiotensin converting enzyme inhibitors and/or angiotensin II receptor blockers, that can minimize secondary glomerular injury. Proteinuria has been shown to be an adverse prognostic factor in IgAN, with a strong relationship between proteinuria and prognosis and established importance of remission. Consequently, targeting proteinuria may be a valid surrogate for individualized kidney protective therapy.