Urine flow rate
Urine flow rate or urinary flow rate is the volumetric flow rate of urine during urination. It is a measure of the quantity of urine excreted in a specified period of time (per second or per minute). It is measured with uroflowmetry, a type of flowmetry.
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), that is, V̇ ("V-dot"). Qmax indicates the maximum flow rate. Qmax is used as an indicator for the diagnosis of enlarged prostate. A lower Qmax may indicate that the enlarged prostate puts pressure on the urethra, partially occluding it.
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 is influenced, although not statistically by voiding position. In a meta-analysis on the influence of voiding position in males on urodynamics, 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.
- "MedlinePlus Medical Encyclopedia: Uroflowmetry". From MedlinePlus, a service by the National Institutes of Health. Updated by: David C. Dugdale. Also reviewed by David Zieve. Update Date: 9/3/2010. Retrieved 2012-10-03.
- de Jong, Y; Pinckaers, JH; Ten Brinck, RM; Lycklama À Nijeholt, AA; Dekkers, OM (2014). "Urinating Standing versus Sitting: Position Is of Influence in Men with Prostate Enlargement. A Systematic Review and Meta-Analysis". PLOS ONE. 9 (7): e101320. doi:10.1371/journal.pone.0101320. PMC 4106761. PMID 25051345.