Glomerulonephritis - post-streptococcal

Alternative names
Post-streptococcal GN; Post-infectious glomerulonephritis

Definition
Post-streptococcal GN is a disorder of the kidneys. It involves inflammation of the glomeruli after infection with certain strains of the streptococcus bacterium.

Causes, incidence, and risk factors
Post-streptococcal glomerulonephritis is now an uncommon form of glomerulonephritis. It is the result of an infection, not of the kidneys, but of a remote site such as the skin or pharynx, with a specific type of Group A hemolytic streptococcus bacterium.

As a consequence of trapping immune complexes (formed from streptococcal antigen, antibodies, and complement) in the glomeruli of the kidneys, the glomeruli become inflamed, causing inefficient filtering and excreting function by the kidneys. Protein and blood may be present in the urine, and excess fluid commonly accumulates in the body. Hypertension (high blood pressure) is usually present.

Post-streptococcal glomerulonephritis now occurs less frequently because infections which may make a person vulnerable to the disorder are commonly treated with antibiotics. The disorder may develop 1 to 2 weeks after an untreated throat infection, or 3 to 4 weeks after a skin infection. It may occur in people of any age, especially children 6 to 10 years old. Although skin and throat infections are not uncommon in children, post-infectious GN is a rare complication of these infections.

Risk factors include having a recent history of sore throat, strep throat, streptococcal skin infections (such as impetigo), and other streptococcal infections.

Symptoms

     
  • Visible blood in the urine  
  • Smoky urine  
  • Rust-colored urine  
  • Decreased urine output  
  • Edema (swelling)       o Swelling of the face or eyes (common)       o Swelling of the feet, ankles, extremities       o Swelling of the abdomen       o Generalized swelling  
  • Cough, with sputum

Additional symptoms that may be associated with this disease:

     
  • Joint stiffness  
  • Joint pain

Signs and tests
An examination shows edema, especially of the face. Generalized, peripheral, or dependent edema may also appear. Circulatory congestion is common, with associated abnormal sounds heard when listening to the heart and lungs with a stethoscope (auscultation). The blood pressure is often high.

     
  • Urinalysis shows white blood cells, casts, and other abnormalities.  
  • Urine protein may be present, but is usually less than with nephrotic syndrome.  
  • Urine sodium may be low.  
  • Serum ASO may be elevated.  
  • Serum complement levels usually decrease.  
  • Kidney biopsy confirms post-streptococcal glomerulonephritis, but biopsy is not usually necessary.  
  • The results of an anti-DNase B test may be abnormal.

Treatment
There is no specific treatment for post-streptococcal glomerulonephritis. Treatment is focused on relief of symptoms.

Antibiotics, such as penicillin, should be used to destroy any streptococcal bacteria that remain in the body. Antihypertensive medications and diuretic medications may be needed to control swelling and high blood pressure. Corticosteroids and other anti-inflammatory medications are generally not effective.

Dietary salt restriction may be necessary to control swelling and high blood pressure.

Expectations (prognosis)
Post-streptococcal glomerulonephritis usually resolves spontaneously after several weeks to months. In a minority of adults, it may progress to chronic renal failure.

Complications

     
  • Acute renal failure  
  • Hyperkalemia  
  • Nephrotic syndrome  
  • Chronic glomerulonephritis  
  • Chronic renal failure  
  • End-stage renal disease  
  • Hypertension  
  • Congestive heart failure or pulmonary edema

Calling your health care provider
Call your health care provider if symptoms indicate post-streptococcal GN may be present.

If you have experienced post-streptococcal GN, call your health care provider if decreased urine output or other new symptoms occur.

Prevention
Adequate treatment of known streptococcal infections may prevent post-streptococcal glomerulonephritis.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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