Proton pump inhibitors and acute interstitial nephritis

Since the introduction of omeprazole in 1989, proton pump inhibitors (PPIs) have become one of the most widely prescribed classes of drugs. A community database of patients who have had any renal function tests in our region shows a prescription rate of 8% (C Farmer, personal communication, 2010). Proton pump inhibitors are associated with a range of side effects including hip fracture, Clostridium difficile infection, and hypomagnesaemia.1 2 3 Sporadic case series have implicated them as a potential cause of acute interstitial nephritis leading to acute kidney injury.4 5 6

In southeast England during 2007 and 2008, we examined 210 kidney biopsies and found six cases of acute interstitial nephritis that were strongly associated with PPIs either by temporal association with the injury or response to stopping the drugs. These patients had biopsies because renal function was declining, the cause was uncertain, and screening for acute kidney injury was negative. The table⇓ summarises five of the six cases of acute interstitial nephritis associated with PPIs (one patient did not consent to be included), and we present two of the cases.