What Is Interstitial Nephritis?

Medically Reviewed by Sanjay Ponkshe on February 24, 2024
Written by Lilianna Hogan
3 min read

Interstitial nephritis is a condition in which a small part of your kidneys’ filters, called the tubules, gets swollen. It can be mild and short-term or more severe and longer-term. It is usually caused by another disease.

What Are the Types of Interstitial Nephritis?

There are two types of interstitial nephritis. They are:

  • Acute interstitial nephritis. This type comes on quickly. You either can’t pee enough or pee too much, especially at night. If your acute interstitial nephritis is caused by bacterial infection, you may have a fever, pain when urinating, and back pain. 
  • Chronic tubulointerstitial nephritis. This type develops gradually. Its symptoms ⁠— itchiness, fatigue, appetite changes, nausea, vomiting, and breathing issues ⁠— can at first look like kidney failure. Usually, urine is excessive, and there are problems breathing. 

The most common causes of interstitial nephritis are:

  • Drugs. Drugs associated with interstitial nephritis are aspirin, antibiotics, nonsteroidal anti-inflammatory medications, proton pump inhibitors, and immune checkpoint inhibitors.
  • Drug reactions. Interstitial nephritis can be caused by an allergic reaction to a medication. 
  • Infections. Bacterial infections like E. coli, viral infections like HIV or herpes, syphilis, parasites, and exposure to fungi are all infections that are linked to interstitial nephritis. Kidney infections also cause interstitial nephritis.
  • Immune disorders. Sarcoidosis, Sjogren’s syndrome, and lupus are all linked to interstitial nephritis. 

Interstitial nephritis symptoms include:

  • Reduced amount of urine 
  • Increased urine 
  • Nausea
  • Vomiting
  • Fever
  • Rashes
  • High blood pressure
  • Irregular mood swings
  • Drowsiness 
  • Confusion 
  • Swelling throughout your body 
  • Weight gain

Most people do not have any or very few symptoms.

If you have chronic tubulointerstitial nephritis, you may also have breathing problems.

The only way of getting an accurate interstitial nephritis diagnosis is through various laboratory tests:

  • Kidney function tests. These are blood tests that can detect signs of failure in your kidneys. They can detect waste products, metabolic acidosis, acidosis, uric acid, and phosphate. 
  • Kidney biopsy. This is a test where kidney tissue is removed and then looked at under a microscope. It is the only way to definitely prove that you have interstitial nephritis, but it is performed in rare cases to see if corticosteroids should be prescribed. 
  • Various tests. Other tests your doctor might order include ultrasonography, radionuclide scannings, or a combination of the two. These two tests are for when the cause of your interstitial nephritis is an allergic reaction. They are both tests that can show inflammation in the kidneys. 

The treatment for interstitial nephritis depends on its type and severity:

  • Acute interstitial nephritis. Stop taking the drug that may be causing symptoms. Your doctor may prescribe corticosteroids if the acute interstitial nephritis is the result of a disorder like lupus or an allergic reaction to a medication. If your interstitial nephritis is very severe and your kidneys start to fail, you may need your kidneys to be artificially cleaned by a process called dialysis. 
  • Chronic interstitial nephritis. Stop taking the drug that may be causing symptoms. Your doctor will manage your blood pressure, and you may take medication to slow the progress of the infection. If your kidneys are permanently damaged, you will need to get dialysis or a kidney transplant.