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)
Primary diseases that solely affect the kidneys and
cause AGN, include the
following: - 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.
