Interstitial nephritis

Alternative names:

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

Symptoms:

• increased or decreased urine output
• fever
• mental status changes, ranging from drowsiness to confusion to coma
• nausea, vomiting
• rash (sometimes)
• swelling of the body, any area
• weight gain (from fluid retention)
• blood in the urine

Signs and tests:

An examination may reveal edema or fluid overload, or signs of volume depletion, with abnormal sounds heard when listening with a stethoscope (auscultation) to the heart or lungs. The blood pressure commonly is high.

• A urinalysis shows small amounts of protein and sometimes red blood cells, renal tubular cells, and other abnormalities. The excretion of protein in the urine is not as severe as with nephrotic syndrome.
• Urine specific gravity and osmolality show there is a failure to concentrate urine even when water intake is restricted.
• Urine pH may show a failure to acidify urine appropriately.
• Arterial blood gases and blood chemistry may show metabolic acidosis.
• BUN and creatinine levels are used to assess level of kidney functioning.
• RBC; urine shows increased red blood cells indicating kidney disease.
• A kidney biopsy confirms the diagnosis of interstitial nephritis and is used to evaluate the extent of damage to the kidney.