Urine flow rate

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Parameter Value
renal blood flow RBF=1000 ml/min
hematocrit HCT=40%
renal plasma flow RPF=600 ml/min
filtration fraction FF=20%
glomerular filtration rate GFR=120 ml/min
urine flow rate V=1 mL/min
Sodium Inulin Creatinine PAH
SNa=150 mEq/L SIn=1 mg/mL SCr=0.01 mg/ml SPAH=
UNa=710 mEq/L UIn=150 mg/mL UCr=1.25 mg/mL UPAH=
CNa=5 mL/min CIn=150 ml/min CCr=125 mL/min CPAH=420 ml/min
ERPF=540 ml/min

Urine flow rate (or urinary flow rate, uroflowmetry) is a measure of the quantity of urine excreted in a specified period of time. Common periods of time used include "minute" and "seconds."

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

It can be estimated by uroflowmetry (or "uroflow"), which is performed by urinating into a special urinal or toilet that has a measuring device or a disposable device.[1] The average rate changes with age.[1]

Clinical usage[edit]

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.[2]

See also[edit]


  1. ^ a b "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. 
  2. ^ 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.