Post-streptococcal GN

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.

Alternative Names:

Glomerulonephritis - post-streptococcal; Post-infectious glomerulonephritis

Causes, incidence, and risk factors:

Post-streptococcal glomerulonephritis is 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 hemolytic streptococcus bacterium.

As a consequence of immune complexes (formed from streptococcal antigen , antibodies , and a substance called complement ) becoming trapped in the glomeruli of the kidneys, the glomeruli become inflamed. This results in 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 is uncommon these days because infections that can make a person vulnerable 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 6-10 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)
  • Swelling of the face or eyes (common)
  • Swelling of the feet, ankles, extremities
  • Swelling of the abdomen
  • 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 (swelling), especially of the face. Generalized, peripheral, or dependent edema may also appear. Circulatory congestion is common. This causes abnormal sounds to be heard when listening to the heart and lungs with a stethoscope ( auscultation ). The blood pressure is often high.

• Urinalysis shows blood protein and white blood cells.
• 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 goes away by itself 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 suggest post-streptococcal GN.

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.