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)
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.
