Jan 25 2009
Interstitial Nephritis
Interstitial nephritis (IN): an accute, often drug-induced renal disease that involves inflammatory damage to interstitial tissue.
This condition can have a crippling impact on kidney function. Damage to interstitial tissue is the second most common cause of chronic renal failure (following glomerular disease). Causes of IN include infection (streptococcal, for example) and drug use. Among the drugs that commonly contribute to this condition are the following antibiotics:
- Methicillin
- Ampicillin
- Sulfonamides
- Phenindione
- Phenytoin
Interstitial nephritis may also arise from idiopathic causes. Early detection of infections, drug reactions, and urinary tract obstruction is key. Medical professionals routinely take into account taht some patients may abuse over-the-counter analgesics when diagnosing this condition.
Pathophysiology
Acute inflammation of the interstitium may cause scarring and rapid decline in kidney function. As many as 10-15% of the cases of acute renal failure may be associated with acute interstitial nephritis. The inflammatory process is generally diffuse and accompanied by interstitial dedema. An immune response appears to casue acute IN that may involve disposition of both immune complexes as well as antitubular basement membrane antibodies.
Chronic IN results in a shrunken kidney with an irregular outline, due to the scarring and tissue destruction it has endured. It follows a slowly progressive course with very few clincial manifestations. Changes in renal hormone activity may occur, and the production of renin, erythropoietin, and vitamin D may be reduced. The ability to concentrate urin is also stifled. The most common causes of IN are anatomic abnormalities (such as an obstruction in the urinary tract), hyperuricemia, analgesic use, and nephrosclerosis.