oliguri

Oliguri, sometimes written as oliguria, is the clinical term for abnormally low urine production. In adults it is commonly defined as urine output less than 400 mL per day or less than 0.5 mL per kilogram of body weight per hour for several hours. Thresholds differ in children and infants, where weight-based criteria are used. The condition signals impaired kidney function or disturbances in urine formation.

Oliguri is usually categorized by the underlying mechanism into pre-renal, renal (intrinsic), and post-renal causes. Pre-renal oliguria results from reduced renal perfusion, such as volume depletion from dehydration or blood loss, or from systemic conditions like heart failure or shock. Renal oliguria stems from intrinsic kidney injury or disease, including acute kidney injury due to ischemia, nephrotoxins, glomerulonephritis, or acute tubular injury. Post-renal oliguria arises from urinary tract obstruction—stones, tumors, enlarged prostate, or bladder outlet dysfunction—that prevents urine flow despite ongoing production.

Assessment typically includes monitoring urine output alongside intake, vital signs, and fluid status. Laboratory evaluation covers serum creatinine, blood urea nitrogen, electrolytes, and urinalysis; measurements of urine sodium and osmolality can help distinguish prerenal from renal causes. Imaging, most commonly renal ultrasound, is used to evaluate for obstruction or structural abnormalities.

Management targets the underlying cause while maintaining fluid and electrolyte balance. In prerenal states, judicious fluid resuscitation and hemodynamic optimization are key. Intrinsic kidney injuries may require avoidance of nephrotoxins, correction of electrolyte disturbances, and, in severe cases, renal replacement therapy such as dialysis. Obstructive post-renal failure is relieved by drainage or surgical intervention. Prognosis depends on the etiology and duration of reduced output, with rapid correction of reversible causes improving outcomes.

Oliguri is a common clinical finding in hospitalized patients, particularly those with acute illness, dehydration, or kidney impairment. The term emphasizes the need for timely evaluation to prevent progression to more severe kidney dysfunction.