Interstitial nephritis

Alternative names:

acute interstitial (allergic) nephritis; nephritis - interstitial; tubulointerstitial nephritis

Definition:

A kidney disorder caused by inflammation of the tubules and the spaces between the tubules and the glomeruli.

Causes, incidence, and risk factors:

Interstitial nephritis involves inflammation of the spaces between the renal tubules and may include inflammation of the tubules. It may be a temporary lesion, most often associated with the effects of various medications on the kidney, or it may be chronic and progressive.

Interstitial nephritis is one of the lesions associated with analgesic nephropathy, and can also occur with allergic reaction to a drug (acute interstitial allergic nephritis) or as a side effect of medications. Medications commonly associated with interstitial nephritis include antibiotics such as penicillin, ampicillin, methicillin, sulfonamide medications, and others. Other medications include nonsteroidal antiinflammatory drugs, furosemide, and Thiazide diuretics. The disorder may occur 15 or more days after exposure to the medication.

Interstitial nephritis causes reduction in kidney function, ranging from mild dysfunction to acute kidney failure. About one-half of the cases will exhibit decreased urine output and other signs of acute renal failure. The kidney may fail to concentrate the urine when water intake is reduced. The kidney may fail to regulate acid/base levels of the body may be reduced, with failure to excrete acid appropriately in the urine. Metabolic acidosis may occur because of the inability to excrete acid. The disorder may progress to chronic renal failure or end-stage renal disease.

Interstitial nephritis is uncommon, occurring in about 4 out of 100,000 people. Risks include analgesic nephropathy and exposure to medications that may have nephrotoxic effects. The disorder is more severe and more likely to involve chronic or permanent kidney damage in the elderly.