Anuria

Definition

Anuria is defined as urine production of less than 100 mL in 24 hours (some sources use less than 50 mL). It is a critical indicator of severe kidney dysfunction, urinary tract obstruction, or inadequate renal perfusion.

Causes

• Pre-renal: Severe hypovolemia, shock, renal artery occlusion.
• Intrarenal: Acute tubular necrosis, glomerulonephritis, nephrotoxic drugs.
• Post-renal: Bilateral ureteral obstruction, bladder outlet obstruction, blocked catheter.

Clinical Significance

Anuria signals acute kidney injury (AKI) and can rapidly progress to life-threatening complications: fluid overload, hyperkalemia, metabolic acidosis, and uremia. Immediate identification of reversible causes (obstruction, hypovolemia) is critical.

Nursing Interventions

Assess bladder distention and ensure Foley catheter patency (irrigate per order). Monitor strict I&O, daily weights, vital signs, and serum electrolytes (especially potassium). Restrict fluids and potassium as ordered. Prepare for renal replacement therapy (dialysis) if electrolyte or acid-base derangements worsen.

NCLEX Relevance

Recognize anuria as a red-flag AKI cue. Differentiate from oliguria (less than 400 mL/day) and polyuria.