Anuric

Anuric is an adjective describing a state in which the kidneys produce little or no urine. The term derives from Greek, with an- meaning without and ouron meaning urine. In clinical contexts, anuria is often defined as urine output less than 100 milliliters per day, or as complete absence of urine in a 24-hour period. It is distinct from oliguria, which denotes reduced but not absent urine production.

Causes of anuria are generally categorized as pre-renal, post-renal, or intrinsic renal. Pre-renal causes include severe dehydration, shock, or profound volume depletion that markedly reduces renal perfusion. Post-renal causes involve obstruction of the urinary tract, such as bilateral urethral obstruction, bladder neck obstruction, or large obstructing stones, which prevent urine from exiting the kidneys. Intrinsic renal causes encompass acute kidney injury from conditions such as acute tubular necrosis, glomerulonephritis, or acute interstitial nephritis, as well as nephrotoxic injury from medications or toxins, rhabdomyolysis, or severe intrarenal inflammation.

Diagnosis involves confirming very low urine output and assessing kidney function through laboratory tests (serum creatinine and electrolytes), urinalysis, and imaging. Urgent evaluation for reversible causes is essential, including urinary catheterization to assess output, ultrasound or other imaging to detect obstruction, and laboratory tests to identify electrolyte disturbances or signs of kidney injury.

Management focuses on treating the underlying cause and supporting organ function. This may include relieving obstruction with catheterization or surgical intervention, optimizing fluid status, correcting electrolyte and acid–base imbalances, and initiating dialysis when indicated (for hyperkalemia, severe acidosis, volume overload, or uremia). The prognosis depends on the cause and the speed of restoration of urine output.