Rapidly Progressive Glomerulonephritis

Rapidly Progressive Glomerulonephritis

Alternate Names

  • RPGN
  • crescentic glomerulonephritis

Definition

Rapidly progressive glomerulonephritis (RPGN) is a rapid deterioration in kidney function that occurs over weeks to at most a few months. The injury takes place in the filtering portion of the kidneys called "glomeruli" and may be the result of many different processes.

What is going on in the body?

RPGN is linked to an immune reaction against specific parts of the glomerulus, the filtering unit of the kidney. Antibodies that form against one part of the glomerulus (called "basement membrane"), or against other targets in glomeruli ( some directed against "self" called autoimmune), or associated with antibodies called "ANCAs," either directly damage or become trapped in the glomeruli.
The resulting inflammation causes protein and blood to be excreted in the urine. The ability of the kidneys to get rid of toxic wastes is impaired and without timely treatment the kidneys may be damaged beyond repair.

Risks

What are the causes and risks of the disease?

The causes of RPGN include:
  • systemic lupus erythematosus (SLE), an autoimmune disorder in which the person (more often women than men) produces antibodies against his or her own tissue
  • hepatitis (can be hepatitis B and/or C).
  • infection, such as endocarditis, an inflammation in the heart.
  • other infections, such as streptococcal throat infections.
  • a result of other kidney diseases like Berger's disease.
RPGN may also be the result of diseases that are not completely understood. Some of these are: Goodpasture Syndrome, Wegeners, Henoch-Schonlein, as well as others.
When a cause cannot be identified, the RPGN is called idiopathic.

Prevention

What can be done to prevent the disease?

Depending on the cause, some cases of RPGN may be prevented. Early treatment of other conditions, such as systemic lupus erythmatosus may help prevent RPGN. In other cases (Henoch-Schonlein, for example), RPGN cannot be prevented.

Diagnosed

How is the disease diagnosed?

Diagnosis of RPGN starts with a medical history and a complete physical exam. Urine tests will also be done. Higher levels of protein and red blood cells in the urine may indicate the presence of RPGN, especially if kidney function has deteriorated over the correct time frame (over weeks to a few months).
ANCA tests of the blood identify 2 major types of this antibody ("C" and "P") which are associated with RPGN.
The specific diagnosis is confirmed by a kidney biopsy. The biopsy is very useful, because it can show the type (three major categories: antibodies against the glomerular basement membrane, antigen-antibody trapped in the glomerulus, and ANCA+ RPGN) and severity of disease (number of crescents, something pathologists identify).
Other laboratory tests (called complement or tests for lupus or similar autoimmune diseases, and tests for hepatitis B or C)) and blood cultures (for endocarditis if suspected) may also be done.

Long Term Effects

What are the long-term effects of the disease?

Long-term effects of RPGN may vary, depending on the underlying cause. For example, hepatitis may cause long-term effects both in the liver and kidneys. An infection that is treated promptly may cure the cause of the RPGN, and there may be no long-term effects.
However, most people have already sustained significant kidney damage by the time they seek help. Even with treatment, patients can lose kidney function and require dialysis and/or transplant. The longer the condition goes untreated, the more devastating it can be. In other diseases, like Goodpasture Syndrome and Wegeners, involvement of the lungs may lead to severe injury and/or death.

Other Risks

What are the risks to others?

RPGN is not contagious by itself, but the underlying cause may be contagious. For example, if cause of the RPGN is hepatitis C, the hepatitis can be spread to others.

Treatments

What are the treatments for the disease?

Treatment of RPGN depends on the underlying cause. Corticosteroids or other medications that suppress the immune system are usually used.
Immune suppressant medications (azathioprine <i.e., Azasan, Imuran>, methotrexate <i.e., Trexall>, mycophenolate <i.e., CellCept>, and others) are taken.
Wegeners requires treatment with cyclophosphamide (i.e., Cytoxan) a potent immune suppressant.
Plasmapheresis, or blood filtering to remove antibodies and inflammatory agents\, may be done (in Goodpasture Syndrome).
The person may require bed rest, restricted fluid and salt intake, and dialysis. Treatment for the underlying cause, such as antibiotics for a strep infection, may also be needed.
Specific therapies for the hepatitis virus (like interferon and ribavarin for hepatitis C) may be used too.

Side Effects

What are the side effects of the treatments?

Corticosteroids can cause fluid retention, swelling, weight gain, and increased risk of infection. Taking corticosteroids for a long time can cause osteoporosis, or bone thinning.
Some of the more aggressive medication treatments (immune suppressants) may increase the risk of infections and cancer.

After Treatment

What happens after treatment for the disease?

Early treatment of RPGN is essential in an effort (not always successful) to avoid serious kidney damage. Severe RPGN can result in end-stage renal disease. Even with treatment, other organs that are involved may not improve.

Monitor

How is the disease monitored?

Close follow-up with the healthcare provider is needed. Regular blood tests can help monitor for recurrences of RPGN or the disease that caused it (Lupus, Wegeners, Goodpasture Syndrome, etc.).
Kidney function and other tests (like the ANCAs) should also be monitored regularly. Any new or worsening symptoms should be reported to the healthcare provider.

Sources

[hyperLink url="http://www.aafp.org/afp/20000401/2077.html" linkTitle="www.aafp.org/afp/20000401/2077.html"]www.aafp.org/afp/20000401/2077.html[/hyperLink]

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