Post-streptococcal glomerulonephritis (GN)

Definition

Post-streptococcal glomerulonephritis (GN) is a disorder of the kidneys that occurs after infection with certain strains of Streptococcus bacteria.

Alternative Names

Glomerulonephritis - post-streptococcal; Post-infectious glomerulonephritis

Causes, incidence, and risk factors

Post-streptococcal GN is a form of glomerulonephritis. It is the result of an infection, not of the kidneys, but of a completely different area, such as the skin or throat, with a specific type of Group A beta hemolytic streptococcus bacteria.

The strep bacterial infection causes the tiny blood vessels called glomeruli in the kidneys to become inflamed, making the kidneys less able to filter and control the content of the urine.

Post-streptococcal GN is uncommon these days because infections that can lead to the disorder are commonly treated with antibiotics. The disorder may develop 1 - 2 weeks after an untreated throat infection, or 3 - 4 weeks after a skin infection.

It may occur in people of any age, but most often occurs in children ages 6 - 10. Although skin and throat infections are not uncommon in children, post-streptococcal glomerulonephritis is a rare complication of these infections.

Risk factors include:

• Strep throat
• Streptococcal skin infections (such as impetigo)

Symptoms

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

Other symptoms that may be associated with this disease:

• Joint pain
• Joint stiffness or swelling

Signs and tests

• Abnormal sounds may be heard when listening to the heart and lungs with a stethoscope (auscultation).
• Anti-DNase B test may be abnormal.
• Blood pressure is often high.
• Kidney biopsy confirms post-streptococcal GN (although biopsy is not usually necessary). Physical examination shows swelling (edema), especially of the face
• Serum ASO may be raised.
• Serum complement levels usually decrease.
• Urinalysis shows protein and blood in the urine.

Treatment

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

Antibiotics, such as penicillin, should be used to destroy any streptococcal bacteria that remain in the body. Blood pressure 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.

Support Groups

Expectations (prognosis)

Post-streptococcal glomerulonephritis usually goes away by itself after several weeks to months. In a minority of adults, it may progress to chronic kidney failure.

Complications

• Acute renal failure
• Chronic glomerulonephritis
• Chronic renal failure
• Congestive heart failure or pulmonary edema
• End-stage renal disease
• Hyperkalemia
• High blood pressure (hypertension)
• Nephrotic syndrome

Calling your health care provider

Call your health care provider if you have symptoms of post-streptococcal GN.

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

Prevention

Treating known streptococcal infections may prevent post-streptococcal GN.

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References

Appel GB. Glomerular disorders and nephrotic syndromes. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 122.