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 ). I ...

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 excretion, excreted from the body through the urethra. Cel ...

during

urination Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...

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

second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ...

or per

minute The minute is a unit of time usually equal to (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a nega ...

). It is measured with uroflowmetry, a type of

flow measurement Flow measurement is the quantification of bulk fluid movement. Flow can be measured in a variety of ways. The common types of flowmeters with industrial applications are listed below: * a) Obstruction type (differential pressure or variable area ...

. 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 is usually reserved for the ''interpunct'' ( · ), or to the glyphs "combining dot above" ( ◌̇ ) and "combining dot below" ( ◌̣ ) which may be combined with some letters of the ...

), 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 loss o ...

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

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...

, 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, inability to urinate, or loss o ...

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

meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Meta-analyses can be performed when there are multiple scientific studies addressing the same question, with each individual study reporting me ...

on the influence of voiding position in males on

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

, 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