Acute interstitial nephritis

What it is

Acute interstitial nephritis is one of the intrinsic causes of acute kidney injury. Intrinsic renal failure is most commonly acute tubular necrosis, from ischemia or toxins, and less commonly acute glomerulonephritis, such as RPGN or hemolytic uremic syndrome, or acute interstitial nephritis. Acute kidney injury itself is an abrupt decline in renal function measured by a rising creatinine and BUN or by oliguria or anuria.

Causes and risk

Drugs are the cause. The named ones are penicillins, TMP-SMX, cephalosporins and NSAIDs. A mnemonic groups the drugs as five P's:

• Pee, for diuretics.
• Pain-free, for NSAIDs.
• Penicillins, with cephalosporins and TMP-SMX.
• Proton pump inhibitors.
• Rifampin.

How it presents

The clinical picture is a new drug exposure with a maculopapular rash and fever, with arthralgias in some, and an acute kidney injury.