Diuresis

Diuresis is the increased production of urine by the kidney.

Types and causes
The kidney normally produces up to 180 L of "pro-urine" (glomerular filtrate) per day, but reabsorbs most of this before entering the calyx of the kidney. No more reabsorbtion takes place past this point.

Polyuria is increased diuresis. This may be due to large fluid intake, various illnesses (diabetes insipidus, osmotic diuresis due to diabetes mellitus or hypercalcemia) or various chemical substances (diuretics, caffeine, alcohol). It may also occur after supraventricular tachycardias, during an onset of atrial fibrillation, childbirth, and the removal of an obstruction within the urinary tract.

Diuresis is restrained by antidiuretics such as ADH, angiotensin II and aldosterone.

Cold diuresis is the occurrence of increased urine production on exposure to cold, which also partially explains immersion diuresis.

Substances that increase diuresis are called diuretics. Caffeine is an example of a diuretic.

Substances that decrease diuresis allow more vasopressin or antidiuretic hormone (ADH) to be present in the kidney.

High-altitude diuresis occurs at altitudes above 10,000 ft and is a desirable indicator of adaptation to high altitudes. Mountaineers who are adapting well to high altitudes experience this type of diuresis. Persons who produce less urine even in the presence of adequate fluid intake probably are not adapting well to altitude.