Interstitial Nephritis

Interstitial nephritis can be classified based on duration and cause:

• Based on duration
  • Acute interstitial nephritis (AIN): It develops suddenly and is often triggered by drugs, infections, or transplant reactions. Symptoms appear quickly and may include reduced kidney function.
  • Chronic interstitial nephritis (CIN): It develops gradually over months or years, usually due to long-term exposure to toxins, medications, or chronic infections. Kidney damage progresses gradually.
• Based on cause
  • Drug-inducedinterstitial nephritis: It is induced by medications, such as antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), or proton pump inhibitors.
  • Infection-related interstitial nephritis: It is triggered by bacterial, viral, or other infections.
  • Autoimmune or systemic disease-related interstitial nephritis: It is seen in conditions such as lupus or sarcoidosis.
  • Idiopathic interstitial nephritis: It is a type of interstitial nephritis for which the cause is unknown.

Acute interstitial nephritis may sometimes be asymptomatic and patients may have a normal urine output. However, blood tests often reveal declining kidney dysfunction.

Symptoms may vary depending on the cause and severity and can include:

• Decreased urine output or changes in urine colour
• Fatigue or general weakness
• Nausea or vomiting
• Fever and back pain
• Itchiness or skin rash, especially if caused by medications
• Swelling in the legs, ankles, or around the eyes
• Haematuria (blood in the urine)
• Proteinuria (protein in the urine)

Common causes of acute interstitial nephritis include:

• Medications such as antibiotics or non-steroidal anti-inflammatory drugs (NSAIDs)
• Bacterial, viral, or other infections
• Autoimmune conditions such as lupus or sarcoidosis
• Reactions following kidney transplants.

The following investigations are performed to diagnose interstitial nephritis:

• Blood tests to check kidney function and detect inflammation
• Urine tests to look for blood, protein, or white blood cells
• Imaging studies such as ultrasound to examine kidney structure
• USG-guided kidney biopsy to confirm the diagnosis

Treatment for this condition focuses on addressing the cause and supporting kidney function:

• Stopping or changing any medication that triggered that condition
• Treating infections if present
• Using corticosteroids or other immunosuppressive medications in selected cases
• Dialysis in severe cases where kidney function is significantly impaired

A doctor should be consulted if you notice any of the below symptoms:

• Sudden reduction in urine output
• Swelling in legs, face, or hands
• Blood in urine
• Fever, rash, or unexplained fatigue
• Nausea or vomiting along with urinary changes

Taking some preventive measures can help reduce the risk of interstitial nephritis and protect kidney health:

• Avoid long-term use of medications that can harm the kidneys unless prescribed and regularly monitored by a doctor.
• Seek prompt treatment for infections to prevent kidney complications.
• Have regular check-ups if you have chronic conditions or a personal or family history of kidney problems.

A nephrologist (kidney specialist) should be consulted for proper evaluation and management of interstitial nephritis.