Definition
Acute poststreptococcal glomerulonephritis (APSGN) is an inflammation of the kidney tubules (glomeruli) that filter waste products from the blood, following a streptococcal infection such as strep throat. APSGN is also called postinfectious glomerulonephritis.
Description
APSGN develops after certain streptococcal bacteria (group A beta-hemolytic streptococci) have infected the skin or throat. Antigens from the dead streptococci clump together with the antibodies that killed them. These clumps are trapped in the kidney tubules, cause the tubules to become inflamed, and impair that organs' ability to filter and eliminate body wastes. The onset of APSGN usually occurs one to six weeks (average two weeks) after the streptococcal infection.
APSGN is a relatively uncommon disease affecting about 1 of every 10,000 people, although four or five times that many may actually be affected by it but show no symptoms. APSGN is most prevalent among boys between the ages of 3 and 7, but it can occur at any age.
Causes & symptoms
Frequent sore throats and a history of streptococcal infection increase the risk of acquiring APSGN. Symptoms of APSGN include:
- Fluid accumulation and tissue swelling (edema) initially in the face and around the eyes, later in the legs
- Low urine output (oliguria)
- Blood in the urine (hematuria)
- Protein in the urine (proteinuria)
- High blood pressure
- Joint pain or stiffness.
Diagnosis
Diagnosis of APSGN is made by taking the patient's history, assessing his/her symptoms, and performing certain laboratory tests. Urinalysis usually shows blood and protein in the urine. Concentrations of urea and creatinine (two waste products normally filtered out of the blood by the kidneys) in the blood are often high, indicating impaired kidney function. A reliable, inexpensive blood test called the anti-streptolysin-O test can confirm that a patient has or has had a streptococcal infection. A throat culture may also show the presence of group A beta-hemolytic streptococci.
Treatment
Treatment of ASPGN is designed to relieve the symptoms and prevent complications. Some patients are advised to stay in bed until they feel better and to restrict fluid and salt intake. Antibiotics may be prescribed to kill any lingering streptococcal bacteria, if their presence is confirmed. Antihypertensives may be given to help control high blood pressure and diuretics may be used to reduce fluid retention and swelling. Kidney dialysis is rarely needed.
Prognosis
Most children (up to 95%) fully recover from APSGN in a matter of weeks or months. Most adults (up to 70%) also recover fully. In those who do not recover fully, chronic or progressive problems of kidney function may occur. Kidney failure may result in some patients.
Prevention
Receiving prompt treatment for streptococcal infections may prevent APSGN.
Key Terms
- Streptococcus
- A gram-positive, round or oval bacteria in the genus . Group A streptococci cause a number of human diseases including strep throat, impetigo, and ASPGN.
Further Reading
For Your Information
Books
- Fauci, Anthony S., et al, eds. Harrison's Principles of Internal Medicine. 14th ed. New York: McGraw-Hill, 1998.
- Professional Guide to Diseases. 5th ed. Springhouse, PA: Springhouse Corp., 1995.
Organizations
- American Kidney Fund. 6110 Executive Boulevard, Rockville, MD 20852. (800) 638-8299.
- National Kidney Foundation. 30 East 33rd Street, New York, NY 10016. (800) 622-9010.
Gale Encyclopedia of Medicine. Gale Research, 1999.
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