Poststreptococcal glomerulonephritis (PSGN) is a specific type of kidney inflammation that affects the filtering portion of the kidney called a glomerulus (plural glomeruli). It is caused by the production of antigen-antibody combinations which get caught in the kidneys filters. The antibodies target parts of a bacterium called Group A beta-hemolytic Streptococcus. This bacterium causes throat and skin infections.
What is going on in the body?
Poststreptococcal glomerulonephritis mostly affects children, two to twelve years of age, who are prone to Streptococcus infections (sore throats and skin infections).
These bacteria are a common cause of sore throat, sometimes called "strep throat." They can also cause the skin infection known as impetigo or Scarlet fever.
When a person has one of these infections, the immune system can sometimes react abnormally and vigorously make antibodies to parts of that bacteria. This reaction can cause inflammation and damage in the kidneys when these antigen-antibody combinations filter out in the kidney.
It is not known why this occurs. Most people recover from PSGN and have no long-term effects. Some, however, get permanent kidney failure from PSGN, especially adults who get this kidney inflammation.
What are the causes and risks of the disease?
PSGN is caused by an infection with certain strains of Streptococcus bacteria that are in Group A. When the infection is in the throat, it's called pharyngitis or "strep throat." When it's on the skin, it's often called impetigo.
Scarlet fever in children is another disease caused by this bacterium. Children between 2 and 10 years old are most commonly affected.
Epidemics may occur if Strep is passed from child to child in enclosed environments, such as day care centers.
Adults with PSGN usually have more serious kidney inflammation than children and are less likely to have a full recovery.
What can be done to prevent the disease?
The only known way to prevent PSGN is to avoid and/or quickly treat strep infections with antibiotics. However, PSGN can occur after antibiotic treatment
How is the disease diagnosed?
Diagnosis of PSGN begins with the history and physical exam. A history of recent sore throat, especially if a throat culture grew Strep, group A, or skin infection and kidney problems about 2 weeks later suggests PSGN.
A urine test called a urinalysis is usually done. This test can show abnormal blood or protein in the urine. A blood test called a complement level may also be done. It is low in this disease. Certain antibodies tests (one called an "ASO") are also obtained. This test helps to confirm that a recent strep infection has occurred.
A person with a questionable picture, unusual, prolonged, or severe symptoms may need a kidney biopsy. This procedure can help figure out the amount and type of kidney damage. It can also help make sure that there are no other conditions causing kidney damage.
Long Term Effects
What are the long-term effects of the disease?
Most people with PSGN, especially children, recover within a few weeks and have no long-term effects. However, some people develop permanent kidney damage and even kidney failure. Those with kidney failure need
dialysis or a kidney transplant to survive. Dialysis is a procedure to filter the blood when the kidneys no longer work. Usually this must continue for the rest of the person's life or until a kidney transplant can be done.
What are the risks to others?
Poststreptococcal glomerulonephritis is not contagious. However, the strep infection that causes this condition is contagious. Those who catch the infection may or may not develop PSGN.
What are the treatments for the disease?
Treatment is usually directed at the symptoms. Many people can be treated at home. Those with more severe symptoms need to stay in the hospital. Limiting fluid and salt intake can help with skin swelling.
Medications called diuretics, such as furosemide (i.e., Lasix), may also be needed for swelling or breathing trouble. Blood pressure medications may be needed for high blood pressure.
Those who develop kidney failure will often need dialysis or a kidney transplant.
What are the side effects of the treatments?
Diuretics may cause allergic reactions, stomach upset, and salt and potassium imbalances. Dialysis requires surgery to get the person ready to be hooked up to the blood-filtering machine. Dialysis can cause sudden salt imbalances and even death. Surgery may cause infections, bleeding, or reactions to anesthesia.
What happens after treatment for the disease?
Most people with PSGN recover completely and need no further treatment. Those who have severe kidney damage may need monitoring and treatment for many years, or even life.
How is the disease monitored?
Many people can be watched by caregivers at home. Any change in symptoms or response to treatment can be reported to the healthcare provider. Those with more serious kidney damage need closer monitoring with blood and urine tests, or admission to the hospital. Blood pressure may also need to be monitored in those with high blood pressure.
Harrison's Principles of Internal Medicine, Fauci et al, 1998