Oliguria

A pathological reduction of urine excretion (oliguria), defined in adults as urine output <400–500 mL/24 hours or <0.5 mL/kg/hour, representing impaired renal perfusion, reduced glomerular filtration, or urinary tract obstruction.

Causes

• Prerenal causes (reduced renal blood flow)

  • Dehydration

  • Hemorrhage

  • Hypovolemia

  • Circulatory shock: sepsis, cardiogenic, anaphylaxis

  • Heart failure

• Intrinsic renal causes (kidney parenchymal injury)

  • Acute kidney injury: Acute tubular necrosis

  • Chronic kidney disease

  • Renal inflammation

  • Nephrotoxic medications: NSAIDs, chemotherapy, antibiotics

  • Toxins and heavy metals

  • Contrast-induced nephropathy

  • Rhabdomyolysis with pigment-induced kidney injury

• Postrenal causes (urinary outflow obstruction)

  • Urolithiasis

  • Benign prostatic hyperplasia

  • Prostate cancer

  • Bladder outlet obstruction

  • Ureteral obstruction

  • Pelvic or retroperitoneal tumors

  • Blood clots obstructing urinary flow

• Other causes

  • Severe infections and systemic inflammatory states

  • Advanced liver disease with hepatorenal syndrome

  • Renal artery stenosis or thrombosis

  • Pregnancy-related renal disorders