Overview

Acute glomerulonephritis (AGN) is active inflammation  in the glomeruli. Each kidney is composed  of about 1 million microscopic filtering "screens" known  as glomeruli that selectively remove uremic waste products. The inflammatory process usually begins  with an infection or injury (e.g., burn, trauma), then  the protective immune system fights off  the infection, scar tissue forms,  and the process is complete. 

There are many diseases that cause an active inflammation within  the glomeruli. Some of these diseases  are systemic (i.e., other parts  of the body are involved at  the same time)  and some occur solely in the glomeruli. When there  is active inflammation within  the kidney, scar tissue  may replace normal, functional kidney tissue and cause irreversible renal impairment. 

The severity and extent  of glomerular damage—focal (confined) or diffuse (widespread)—determines how  the disease is manifested. Glomerular damage can appear as subacute renal failure, progressive chronic renal failure (CRF); or simply a urinary abnormality such as hematuria (blood in  the urine) or proteinuria (excess protein in the urine). 

Causes  

In diffuse glomerulonephritis (GN), all  of the glomeruli are aggressively attacked, leading to acute renal failure (ARF). Disorders that attack several organs  and cause diffuse GN are referred  to as secondary causes. Secondary causes  of diffuse GN include  the following: 

• Cryoglobulinemia  
• Goodpasteur’s syndrome (membranous antiglomerular basement membrane disease) 
• Lupus nephritis 
• Schönlein-Henoch purpura 
• Vasculitis (e.g., Wegener's granulomatosis, periarteritis nodosa) 

• Immunoglobulin A nephropathy (IgA nephropathy, Berger’s disease) 
• Membranoproliferative nephritis (type of kidney inflammation) 
• Postinfectious GN (GN that results after an infection) 

Signs  and Symptoms 

Patients who have secondary causes of AGN often exhibit these symptoms: 

• Cough  with blood-tinged sputum 
• Fever  
• Joint  or muscle pain 
• Rash

Diagnosis 

Patients with acute glomerulonephritis (AGN) have an active urinary sediment. This means  that signs of active kidney inflammation  can be detected when the urine is examined  under the microscope. Such signs include red blood cells, white blood cells, proteinuria (blood proteins  in the urine), and "casts" of cells that have leaked  through the glomeruli and have reached the tubule, where they develop into cylindrical forms. 

A  kidney biopsy is essential to establish a diagnosis of AGN, determine the cause, and create an effective treatment plan. 

Treatment 

The goal of treatment is to stop  the ongoing inflammation  and lessen the degree  of scarring  that ensues. Depending on the diagnosis, there are different treatment strategies. Often the treatment warrants a regimen of immunosuppressive drugs to limit the immune system’s activity. This decreases the degree of inflammation and subsequent irreversible scarring.