Polyuria

The excessive excretion of urine defined as a urine output exceeding 3 liters per 24 hours in adults.

Causes

• Osmotic diuresis causes

  • Uncontrolled diabetes mellitus

  • Glucosuria causing increased urinary water loss

  • High-protein intake or increased urea production

  • Mannitol or other osmotic agents

• Water diuresis causes

  • Central diabetes insipidus

  • Nephrogenic diabetes insipidus

  • Primary polydipsia

  • Psychogenic polydipsia

  • Excessive fluid intake

  • Excessive intake of caffeine or alcohol

• Medications affecting renal water handling

  • Diuretics (loop diuretics, thiazides)

  • Lithium (causing nephrogenic diabetes insipidus)

• Kidney failure with impaired urine concentrating ability

• Metabolic and endocrine causes

  • Hypercalcemia

  • Hypokalemia

  • Hyperthyroidism

  • Disorders affecting antidiuretic hormone regulation