polyuria, daily output of an excessive amount ofurine. In humans, polyuria involves the output of more than three liters of urine per day. Althoughcharacterized in part by needing to void more frequently, polyuria differs from frequenturination, since it also involves increased urine volume. Polyuria is a common symptom of bothtype 1 andtype 2diabetes.

The body produces urine through the filtration ofblood by thekidneys. Specialized functional units in the kidneys known asnephrons filter initial urine from nutrients. Within nephrons, structures known as the glomerulus and renal tubules extract nutrients such asamino acids,electrolytes, andglucose, separating them from water and waste products. Waste products exit the body with water in the form of urine, while nutrients are returned to the bloodstream.

There are several causes of polyuria. These include polydipsia (excessive intake of fluids) and the intake of beverages containingcaffeine oralcohol. Reduced production ofantidiuretic hormone (ADH), which regulates reabsorption of water in the kidneys, can result in excessive urine production. Polyuria also occurs when the renal tubules suffer decreased sensitivity to ADH. A condition known as solute diuresis, which often occurs withdiabetes, results from limited absorptive ability of the renal tubules. Thus, when excess amounts of certain solutes, such as electrolytes orsodium chloride, pass through the tubules, they pull water from the body, causing an increase in urine volume. Medications that act asdiuretics, which are used to treat conditions such ashigh blood pressure andliver failure, also increase urination; indeed, diuretics are the most common cause of polyuria in adults. In addition to diabetes, other diseases and conditions are associated with polyuria. For example, polyuria often occurs in thecontext of hypercalcemia (excesscalcium in the blood),pregnancy,kidney disease, and liver failure. It is also a symptom of theautoimmune disordersSjögren syndrome andsarcoidosis.

Treatment for polyuria depends on the cause. For some persons, reducing intake of alcohol and caffeine can help with managing the condition. In patients with diabetes, symptoms of polyuria often improve when medicationregimens are adjusted to better control diabetes.