Acute interstitial nephritis (AIN)
This is a short page about Acute Interstitial Nephritis (AIN), which means inflammation in the tubules (the tiny tubes that take urine from the filtering units of the kidney), and the surrounding parts of the kidney. This inflammation is most commonly caused by an allergic reaction to something. We have a separate page on other interstitial kidney diseases, covering all diseases of the tubules of the kidney, or ‘tubulointerstitium’.
What trouble does AIN cause?
It causes the kidneys to work less well and can cause severe kidney failure. Like most diseases affecting the kidney, it produces very few symptoms unless the kidneys are quite severely affected. Some people may get a rash or other symptoms at the same time as the kidney disease, but many people do not get these things.
Blood tests will show abnormal kidney function. Urine tests often show only minor abnormalities, but the urine may contain white blood cells as if it was infected.
What causes AIN?
Most commonly it is an allergic reaction to something, often a medicine. Antibiotics and anti-inflammatory drugs are common causes of this. Occasionally it can even be caused by medicines that you can buy without a prescription, such as the painkiller Ibuprofen (many tradenames, including Nurofen) and other NSAIDs (non-steroidal anti-inflammatory drugs), or Omeprazole and other PPIs (proton pump inhibitors, a type of drug that reduces acid production in the stomach). There is a long list of other medicines that can occasionally cause AIN.
Other causes include
- Infections, caused by common bacteria or occasionally by viruses.
- Autoimmune on its own, or with inflammation of the eyes, which is called TINU Syndrome (Tubulointerstitial Nephritis and Uveitis Syndrome)
- As part of an autoimmune disease which causes inflammation in other parts of the body such as Lupus, or Sarcoidosis.
- There are some other rare causes. See Interstitial kidney diseases for more information.
How is AIN treated?
If the cause is known, it should be removed. If it is a drug, the drug must be stopped and you must never use it again – this means for the rest of your life. AIN occuring a second time could cause more severe kidney damage.
Steroid tablets often speed recovery of AIN caused by allergic reactions to medicines. They may also save some scarring. They work in some other types as well.
Will my kidneys recover?
Usually recovery from AIN is good if it is picked up early. Sometimes there is residual kidney damage which needs to be monitored by blood tests over years to come.
Where can I get further information?
When interstitial inflammation goes on for a long time it becomes Chronic Interstitial Nephritis. The causes include all the things that cause acute interstitial nephritis, plus some others, including toxins. There is more info in our page on Interstitial Kidney Diseases.
Acknowledgements: The author of this page was Neil Turner. It was first published in August 2001. The date is was last modified is shown in the footer.