Acute interstitial nephritis (AIN) is a condition in which there is damage to the tissue surrounding the filtering unit of the kidney. The damage may result in a sudden decline in the kidney function.
What is going on in the body?
In acute interstitial nephritis, different types of white blood cells invade the filtering system of the kidney and cause it to swell. The white blood cells are usually a result of an allergic reaction to a medication, but may also be caused by some infections. Most cases of AIN recover completely. But sometimes, when there has been scarring, the kidney may have irreversible damage.
What are the signs and symptoms of the disease?
Symptoms of acute interstitial nephritis include:
- rash on the trunk, upper arms, and legs
- burning or pain with urination
- back pain or flank pain
- joint pain
- blood in the urine
What are the causes and risks of the disease?
Acute interstitial nephritis may be caused by:
- allergic reaction to certain medications, such as penicillin, cephalosporins, sulfa medications, ibuprofen, thiazide, phenytoin and cimetidine. A person who is exposed over and over to the medication that caused the AIN has a higher risk of infection.
- infection, such as pyelonephritis or infection of the kidney, group A streptococcal infection, diphtheria , and mononucleosis
- autoimmune disorders, such as systemic lupus erythematosus and Sjogren syndrome
Sometimes the cause is unknown.
What can be done to prevent the disease?
Prevention of acute interstitial nephritis is not always possible. It helps to avoid contact with the offending medication, in the case of allergic reaction. Other prevention depends on the underlying cause of infection, such as avoiding exposure to strep infections.
How is the disease diagnosed?
The healthcare provider can usually diagnose AIN by taking a history of the medications the person uses, doing a complete physical exam, and noting the symptoms. Urine and blood tests are done to assess the kidney function and to confirm the diagnosis. Sometimes a skin biopsy of the rash and a kidney biopsy are needed.
What are the long-term effects?
Although most cases of kidney damage are reversible with treatment, a few cases of acute interstitial nephritis may lead to permanent kidney failure.
What are the risks to others?
Acute interstitial nephritis is not contagious and cannot be spread to others. Certain underlying conditions, such as mononucleosis, may be contagious.
What are the treatments?
Treatment will depend on the underlying cause of the acute interstitial nephritis. If the AIN was caused by an allergic reaction to a medication, the kidney function usually returns to normal when the medication is stopped.
If the kidney function does not recover or if the damage is severe, steroids may used to decrease the allergic response. Sometimes short-term dialysis may be needed to remove toxins until the kidney function returns. If the damage to the kidneys is irreversible, the person may need long-term dialysis or a kidney transplant.
What are the side effects of the treatments?
Side effects to steroids may include jitteriness, weight gain, and insomnia. Side effects to surgery may include bleeding, infection, and allergic reaction to anesthesia.
What happens after treatment?
Usually the kidney heals completely and the symptoms of acute interstitial nephritis slowly go away. If surgery is needed, recovery will depend on the extent of surgery.
How is the disease monitored?
The healthcare provider will generally recommend regular visits and kidney function tests. Any new or worsening symptoms should be reported to the healthcare provider.