Polyuria is am excessive or an abnormally large production or passage of urine.



Also called diuresis.



It is greater than 2.5 Lor 3 L over 24 hours in adults.



Often appears in conjunction with polydipsia, an increased thirst.



It is possible to have one without the other.



Polydipsia may lead to polyuria.



Polyuria is usually viewed as a symptom or sign of another disorder.



Polyuria is not a disease by itself.



The most common cause of polyuria is uncontrolled diabetes mellitus.



Polyuria in uncontrolled diabetes mellitus is caused by an  osmotic diuresis, when glucose levels are so high that glucose is excreted in the urine. 



Water follows the high glucose concentration, leading to abnormally high urine output. 



The  other common causes of polyuria: decreased secretion of aldosterone due to adrenal cortical tumor, primary polydipsia, central diabetes insipidus and nephrogenic diabetes insipidus.



Polyuria may also be due to diuretics, caffeine, and ethanol. 



Polyuria also occur with supraventricular tachycardias, during an onset of atrial fibrillation, childbirth, and the removal of an obstruction within the urinary tract. 



Diuresis is controlled by antidiuretics such as vasopressin, angiotensin II and aldosterone. 



Cold diuresis refers to the occurrence of increased urine production on exposure to cold.



High-altitude diuresis occurs at altitudes above 10,000 feet and is a desirable indicator of adaptation to high altitudes. 



Causes of polyuria:



Emphysematous cystitis









psychogenic polydipsia



diuretic drugs, 



osmotic diuresis



interstitial cystitis



urinary tract infection 



renal tubular acidosis



Fanconi syndrome









diabetes mellitus



corticosteroid use









diabetes insipidus












Conn’s disease






congestive heart failure



cardiorespiratory disease



postural orthostatic tachycardia syndrome (POTS)



cerebral salt-wasting syndrome



neurologic damage






high doses of riboflavin



high doses of vitamin D



altitude diuresis



side effect of lithium






Osmotic diuresis polyuria is present when urine osmolarity greater than 300 mOsm/kilogram is indicative of osmotic diuresis.



Polyuria in osmotic cases, increases flow amount in the distal nephron  especially in the cortical-collecting ducts, where flow rates and velocity are low. 



Hyperglycemic and osmotic polyuria play roles in diabetic nephropathy.



Diagnostic tests:



Urine testing



Blood sugar 



Pituitary function tests



Treatment depends on the cause of the polyuria.



Desmopressin can be considered for nocturnal polyuria, which can be caused by diabetes mellitus, if other medical treatments have failed. 



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