urinvolum

Urinary volume, sometimes referred to by the Danish term urinvolum, is the amount of urine produced by the kidneys over a defined time period. It is typically expressed as milliliters or liters per day and can be measured from a single 24-hour collection or as hourly output in clinical settings.

In healthy adults with adequate fluid intake, daily urinary volume usually ranges roughly from 800 to 2000 mL. The typical rate of urine production is about 0.5 mL per kilogram body weight per hour. Oliguria denotes abnormally low urine production (commonly less than about 400 mL per day in adults or less than 0.5 mL/kg/hr in children). Polyuria denotes abnormally high urine production (often more than 2.5–3 L per day). Nocturia refers to waking at night to urinate.

Measurement and monitoring: Clinically, urine volume can be measured by a timed urine collection (24-hour urine) or, in hospitalized patients, by hourly measurements as part of the fluid balance. The accuracy of a 24-hour collection depends on complete collection; in practice, estimated values may be used with caution. Urine output is influenced by hydration status, ambient temperature, and medications such as diuretics.

Physiology and determinants: Urine formation is linked to glomerular filtration rate, renal tubular reabsorption, and hormonal control, notably antidiuretic hormone (vasopressin) and aldosterone. Conditions that affect volume include diabetes mellitus and diabetes insipidus, dehydration, kidney disease, and obstructive uropathy. Drugs like diuretics, caffeine, and alcohol can alter volume.

Clinical significance: Persistent abnormal urinary volume can indicate dehydration, kidney injury, or systemic disorders; urine output is a key parameter in assessing kidney perfusion and overall fluid balance and should be interpreted in conjunction with intake and other clinical data.