diuresis

Diuresis is the increased production of urine by the kidneys. It can occur as a normal physiologic response to higher fluid intake or hormonal signals, or as a pharmacologic or pathologic process that raises urine output.

In the kidney, urine formation is controlled by tubular reabsorption of water and solutes under hormonal regulation. Diuresis occurs when water reabsorption is reduced or when solute load draws water into the filtrate. Diuresis is commonly categorized as osmotic diuresis, caused by non-reabsorbable solutes in the tubular fluid such as glucose or mannitol, and natriuretic diuresis, driven by increased excretion of sodium and water.

Common causes include osmotic diuresis from hyperglycemia in diabetes mellitus or administration of osmotic agents, and diuretic use (loop diuretics, thiazides, acetazolamide, others) that promote solute and water loss. Physiologic reasons include large-volume fluid intake or a transient diuresis after certain procedures. Pathologic contexts include central or nephrogenic diabetes insipidus, post-obstructive diuresis, and other conditions that impair water reabsorption or alter solute handling.

Clinically, diuresis presents as an elevated urine volume, which may be accompanied by dilute urine depending on the mechanism. Evaluation typically involves measuring urine output and osmolality, along with plasma osmolality and electrolytes, to distinguish diuresis from other causes of polyuria and to identify the underlying cause.

Management is cause-directed, focusing on treating the underlying condition, adjusting diuretic therapy when appropriate, and maintaining hydration while monitoring electrolyte balance. Potential complications include dehydration and electrolyte disturbances such as hyponatremia or hypokalemia.