Polyuria () is excessive or an abnormally large production or
passage of
urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
Cellular m ...
(greater than 2.5 L
or 3 L
over 24 hours in adults). Increased production and passage of urine may also be termed
diuresis. Polyuria often appears in conjunction with
polydipsia (increased thirst), though it is possible to have one without the other, and the latter may be a cause or an effect.
Primary polydipsia may lead to polyuria. Polyuria is usually viewed as a
symptom or
sign of another
disorder (not a disease by itself), but it can be classed as a disorder, at least when its underlying causes are not clear.
Causes
The most common cause of polyuria in both adults and children is uncontrolled
diabetes mellitus,
[ which causes osmotic diuresis, when glucose levels are so high that glucose is excreted in the urine. Water follows the glucose concentration passively, leading to abnormally high urine output. In the absence of diabetes mellitus, the most common causes are decreased secretion of aldosterone due to adrenal cortical tumor, primary polydipsia (excessive fluid drinking), ]central diabetes insipidus
Central diabetes insipidus, also called neurogenic diabetes insipidus, is a type of diabetes insipidus due to a lack of vasopressin (ADH) production in the brain. Vasopressin acts to increase the volume of blood (intravascularly), and decrease ...
and nephrogenic diabetes insipidus
Nephrogenic diabetes insipidus, also known as renal diabetes insipidus, is a form of diabetes insipidus primarily due to pathology of the kidney. This is in contrast to central or neurogenic diabetes insipidus, which is caused by insufficient l ...
.[ Polyuria may also be due to various chemical substances, such as ]diuretic
A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics in ...
s, caffeine, and ethanol. 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 controlled by antidiuretic
An antidiuretic is a substance that helps to control fluid balance in an animal's body by reducing urination, opposing diuresis. Its effects are opposite that of a diuretic. The major endogenous antidiuretics are antidiuretic hormone (ADH; also ca ...
s such as vasopressin
Human vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the AVP gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It then travel ...
, angiotensin II
Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the adr ...
and aldosterone
Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a c ...
. ''Cold diuresis'' is the occurrence of increased urine production on exposure to cold, which also partially explains immersion diuresis. ''High-altitude diuresis'' occurs at altitudes above 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 are probably not adapting well to altitude.
List of causes
Mechanism
Polyuria in osmotic cases, increases flow amount in the distal nephron where flow rates and velocity are low. The significant pressure increase occurring in the distal nephron takes place particularly in the cortical-collecting ducts. One study from 2008 lays out a hypothesis that hyperglycaemic and osmotic polyuria play roles ultimately in diabetic nephropathy.
Diagnosis
Among the possible tests to diagnose polyuria are:
Treatment
Depending on the cause of the polyuria, the adequate treatment should be afforded. According to NICE, desmopressin can be considered for nocturnal polyuria, which can be caused by diabetes mellitus, if other medical treatments have failed. The recommendation had no studies that met the criteria for consideration.
See also
* Oliguria
References
Further reading
*
*
External links
{{Urinary system symptoms and signs
Symptoms and signs: Urinary system