Causes
The most common cause of polyuria in both adults and children is uncontrolled diabetes mellitus, causing an osmotic diuresis. In the absence of diabetes mellitus, the most common causes are primary polydipsia (excessive fluid drinking), central diabetes insipidus and nephrogenic diabetes insipidus.
Polyuria may also be due to 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.
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.
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