Urine flow rate or urinary flow rate is the

volumetric flow rate In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol (sometimes \do ...

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

during

urination Urination is the release of urine from the bladder through the urethra in Placentalia, placental mammals, or through the cloaca in other vertebrates. It is the urinary system's form of excretion. It is also known medically as micturition, v ...

. It is a measure of the quantity of urine excreted in a specified period of time (per

second The second (symbol: s) is a unit of time derived from the division of the day first into 24 hours, then to 60 minutes, and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of U ...

or per

minute A minute is a unit of time defined as equal to 60 seconds. It is not a unit in the International System of Units (SI), but is accepted for use with SI. The SI symbol for minutes is min (without a dot). The prime symbol is also sometimes used i ...

). It is measured with uroflowmetry, a type of

flow measurement Flow measurement is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below: * Obstruction type (differential pr ...

. The letters "V" (for volume) and "Q" (a conventional symbol for flow rate) are both used as a symbol for urine flow rate. The V often has a dot (

overdot When used as a diacritic mark, the term dot refers to the glyphs "combining dot above" (, and "combining dot below" ( which may be combined with some letters of the extended Latin alphabets in use in a variety of languages. Similar marks are ...

), that is, V̇ ("V-dot"). Q_max indicates the maximum flow rate. Q_max is used as an indicator for the diagnosis of

enlarged prostate Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or lo ...

. A lower Q_max may indicate that the enlarged prostate puts pressure on the

urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

, partially occluding it. Uroflowmetry is performed by urinating into a special urinal, toilet, or disposable device that has a measuring device built in. The average rate changes with age.

Clinical usage

Changes in the urine flow rate can be indicative of kidney, prostate or other renal disorders. Similarly, by measuring urine flow rate, it is possible to calculate the clearance of metabolites that are used as clinical markers for disease. The urinary flow rate in males with

benign prostate hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, urinary retention, inability t ...

is influenced, although not statistically by voiding position. In a

meta-analysis Meta-analysis is a method of synthesis of quantitative data from multiple independent studies addressing a common research question. An important part of this method involves computing a combined effect size across all of the studies. As such, th ...

on the influence of voiding position in males on

urodynamics Urodynamic testing or urodynamics is a study that assesses how the urinary bladder, bladder and urethra are performing their job of storing and releasing urine. Urodynamic tests can help explain symptoms such as: * Urinary incontinence, inconti ...

, males with this condition showed an improvement of 1.23 ml/s in the sitting position. Healthy, young males were not influenced by changing voiding position.

References

{{DEFAULTSORT:Urine Flow Rate Renal physiology Urine Temporal rates

Clinical usage

See also

References