A renal lesion that typically causes a decline in kidney function and is characterized by an inflammatory infiltrate in the kidney interstitium.

(Causes)
• drug therapy (most often): E.g. antibiotics, nonsteroidal anti-inflammatory drugs, proton-pump inhibitors, diuretics, allopurinol, mesalamine.
• pyelonephritis: A bacterial infection in the kidneys.

Pathogenesis is based on an immunologic reaction against endogenous nephritogenic antigens or exogenous antigens processed by tubular cells, with cell-mediated immunity having a major pathogenic role.
Cell-mediated immunity is an immune response that does not involve antibodies. Rather, cell-mediated immunity is the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
The characteristic interstitial infiltrates, mostly composed of lymphocytes, macrophages, eosinophils, and plasma cells, experience a rapid transformation into areas of interstitial fibrosis.

(Symptoms)
• fever
• skin rash
• nausea, vomiting, fatigue, lack of appetite, weight loss
• arthralgias (joint pain and stiffness)
• flank pain, pain in urination

(Diagnosis)
Blood tests:
• eosinophilia
• hypertension
Urine tests:
• hematuria, red blood cell casts
• white blood cell casts
• eosinophiluria
• sterile pyuria
• low grade proteinuria (majority), nephrotic-range amount of protein (NSAID-associated)
• isosthenuria

(Treatment)
• Identification and removal of the offending drug
• Nutrition therapy: Adequate fluid intake.
• Early steroid administration: Improves the recovery of renal function, decreasing the risk of chronic renal impairment. There is less or no therapeutic benefit when interstitial fibrosis has taken place.

свернуть