Urine is a liquid by-product
in humans and in many other animals. Urine flows from the kidney
s through the ureter
s to the urinary bladder
results in urine being excreted
from the body through the urethra
metabolism generates many by-product
s that are rich in nitrogen
and must be cleared
from the bloodstream
, such as urea
, uric acid
, and creatinine
. These by-products are expelled from the body during urination, which is the primary method for excreting water-soluble chemicals from the body. A urinalysis
can detect nitrogenous waste
s of the mammal
Urine plays an important role in the earth's nitrogen cycle
. In balanced ecosystem
s, urine fertilizes the soil
and thus helps plant
s to grow. Therefore, urine can be used
as a fertilizer
. Some animals use it to mark their territories
. Historically, aged or fermented urine (known as lant
) was also used for gunpowder
production, household cleaning, tanning
of leather and dyeing
Human urine and feces
are collectively referred to as human waste
or human excreta, and are managed via sanitation
urine and feces also require proper management if the livestock population density is high
Most animals have excretory system
s for elimination of soluble toxic wastes. In humans, soluble wastes are excreted primarily by the urinary system
and, to a lesser extent in terms of urea
, removed by perspiration
. The urinary system consists of the kidney
s, urinary bladder
, and urethra
. The system produces urine by a process of filtration
, and tubular secretion
. The kidneys extract the soluble wastes from the bloodstream, as well as excess water, sugars, and a variety of other compounds. The resulting urine contains high concentrations of urea and other substances, including toxins. Urine flows from the kidneys through the ureter, bladder, and finally the urethra before passing from the body.
Research looking at the duration of urination
in a range of mammal
species found that nine larger species urinated for 21 ± 13 seconds irrespective of body size.
Smaller species, including rodent
s and bat
s, cannot produce steady streams and instead urinate with a series of drops
Average urine production in adult humans is around 1.4 L of urine per person per day with a normal range of 0.6 to 2.6 L per person per day, produced in around 6 to 8 urinations per day depending on state of hydration, activity level, environmental factors, weight, and the individual's health.
Producing too much or too little urine needs medical attention. Polyuria
is a condition of excessive production of urine (> 2.5 L/day), oliguria
when < 400 mL are produced, and anuria
being < 100 mL per day.
About 91-96% of urine consists of water.
Urine also contains an assortment of inorganic salts and organic compounds, including proteins, hormones, and a wide range of metabolites, varying by what is introduced into the body.
The total solids in urine are on average 59 g per person per day. Organic matter makes up between 65% and 85% of urine dry solids, with volatile solids comprising 75–85% of total solids. Urea
is the largest constituent of the solids, constituting more than 50% of the total. On an elemental level, human urine contains 6.87 g/L carbon, 8.12 g/L nitrogen, 8.25 g/L oxygen, and 1.51 g/L hydrogen. The exact proportions vary with individuals and with factors such as diet
In healthy persons, urine contains very little protein and an excess
is suggestive of illness.
Urine varies in appearance, depending principally upon a body's level of hydration
, as well as other factors. Normal urine is a transparent solution ranging from colorless to amber but is usually a pale yellow. In the urine of a healthy individual, the color comes primarily from the presence of urobilin
. Urobilin is a final waste product resulting from the breakdown of heme
during the destruction of aging blood cells.
Colorless urine indicates over-hydration, generally preferable to dehydration (though it can remove essential salts from the body). Colorless urine in drug tests can suggest an attempt to avoid detection of illicit drugs in the bloodstream through over-hydration.
* Dark yellow urine is often indicative of dehydration.
* Yellowing/light orange may be caused by removal of excess B vitamin
s from the bloodstream.
* Certain medications such as rifampin
can cause orange urine.
* Bloody urine is termed hematuria
, a symptom of a wide variety of medical conditions.
* Dark orange to brown urine can be a symptom of jaundice
, or Gilbert's syndrome
* Black or dark-colored urine is referred to as melanuria and may be caused by a melanoma
or non-melanin acute intermittent porphyria
* Pinkish urine can result from the consumption of beet
* Greenish urine can result from the consumption of asparagus
or foods or beverages with green dyes.
* Reddish or brown urine may be caused by porphyria
(not to be confused with the harmless, temporary pink or reddish tint caused by beeturia
* Blue urine can be caused by the ingestion of methylene blue
(e.g., in medications) or foods or beverages with blue dyes.
* Blue urine stains can be caused by blue diaper syndrome
* Purple urine may be due to purple urine bag syndrome
File:Dark urine due low fluid intake.jpg|Dark urine due to low fluid intake.
File:HematuriaGross.jpg|Dark red urine due to blood (hematuria).
File:Choluria.svg|Dark red urine due to choluria.
File:Pinkish urine beetroots 1.jpg|Pinkish urine due to consumption of beetroots.
File:IMAG0466.jpg|Green urine during long term infusion of the sedative propofol.
Sometime after leaving the body, urine may acquire a strong "fish-like" odor because of contamination with bacteria that break down urea into ammonia
. This odor is not present in fresh urine of healthy individuals; its presence may be a sign of a urinary tract infection
The odor of normal human urine can reflect what has been consumed or specific diseases. For example, an individual with diabetes mellitus may present a sweetened urine odor. This can be due to kidney diseases as well, such as kidney stones
Eating asparagus can cause a strong odor reminiscent of the vegetable caused by the body's breakdown of asparagusic acid
. Likewise consumption of saffron
, tuna fish
, and onion
can result in telltale scents. Particularly spicy foods can have a similar effect, as their compounds pass through the kidneys without being fully broken down before exiting the body.
(cloudy) urine may be a symptom of a bacterial infection, but can also be caused by crystallization of salts such as calcium phosphate
normally is within the range of 5.5 to 7 with an average of 6.2.
In persons with hyperuricosuria
, acidic urine can contribute to the formation of stones
of uric acid
in the kidneys, ureters, or bladder.
Urine pH can be monitored by a physician or at home.
A diet which is high in protein from meat and dairy, as well as alcohol consumption can reduce urine pH, whilst potassium and organic acids, such as from diets high in fruit and vegetables, can increase the pH and make it more alkaline.
Some drugs also can increase urine pH, including acetazolamide, potassium citrate, and sodium bicarbonate.
Cranberries, popularly thought to decrease the pH of urine, have actually been shown not to acidify urine. Drugs that can decrease urine pH include ammonium chloride
, chlorothiazide diuretics, and methenamine mandelate
Human urine has a specific gravity of 1.003–1.035.
Any deviations may be associated with urinary disorders.
Healthy urine is not toxic. However, it contains compounds eliminated by the body as undesirable, and can be irritating to skin and eyes. With suitable processing, it is possible to extract potable water
Bacteria and pathogens
Urine is not sterile, not even in the bladder. Earlier studies, with less sophisticated analytical techniques, had found that urine was sterile
until it reached the urethra. In the urethra, epithelial cells
lining the urethra are colonized by facultatively anaerobic Gram-negative rod and cocci bacteria
Examination for medical purposes
Many physicians in ancient history resorted to the inspection and examination of the urine of their patients. Hermogenes
wrote about the color and other attributes of urine as indicators of certain diseases. Abdul Malik Ibn Habib of Andalusia
d.862 AD, mentions numerous reports of urine examination throughout the Umayyad
empire. Diabetes mellitus
got its name because the urine is plentiful
. The name ''uroscopy
'' refers to any visual examination of the urine, including microscopy
, although it often refers to the aforementioned prescientific or protoscientific forms of urine examination. Clinical urine tests
today duly note the gross color, turbidity, and odor of urine but also include urinalysis
, which chemically analyzes the urine and quantifies
its constituents. A culture
of the urine is performed when a urinary tract infection
is suspected, as bacteria in the urine
are unusual otherwise. A microscopic examination of the urine may be helpful to identify organic or inorganic substrates and help in the diagnosis.
The color and volume of urine can be reliable indicators of hydration level. Clear and copious urine is generally a sign of adequate hydration. Dark urine is a sign of dehydration
. The exception occurs when diuretics
are consumed, in which case urine can be clear and copious and the person still be dehydrated.
Source of medications
Urine contains proteins and other substances that are useful for medical therapy and are ingredients in many prescription drugs (e.g., Ureacin, Urecholine
, Urowave). Urine from postmenopausal
women is rich in gonadotropin
s that can yield follicle stimulating hormone
and luteinizing hormone
for fertility therapy.
One such commercial product is Pergonal
Urine from pregnant women contains enough human chorionic gonadotropin
s for commercial extraction and purification to produce hCG medication. Pregnant mare urine is the source of estrogen
s, namely Premarin
Urine also contains antibodies
, which can be used in diagnostic antibody tests for a range of pathogen
s, including HIV
Urine can also be used to produce urokinase
, which is used clinically as a thrombolytic
Urine contains large quantities of nitrogen
(mostly as urea
), as well as reasonable quantities of dissolved potassium
. The exact composition of nutrients in urine varies with diet, in particular nitrogen content in urine is related to the quantity of protein
in the diet. A high protein diet results in high urea levels in urine.
Urine is very high in nitrogen (can be over 10% in a high-protein diet), low in phosphorus
(1%), and moderate in potassium (2-3%). Urine typically contributes 70% of the nitrogen
and more than half of the potassium
found in urban wastewater flows, while making up less than 1% of the overall volume. If urine is to be separated and collected for use as a fertiliser in agriculture, then the easiest method of doing so is with sanitation
systems that utilise waterless urinals
, urine-diverting dry toilets (UDDTs)
or urine diversion
[von Münch, E., Winker, M. (2011)]
Technology review of urine diversion components - Overview on urine diversion components such as waterless urinals, urine diversion toilets, urine storage and reuse systems.
Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Undiluted urine can chemically burn the leaves or roots of some plants, particularly if the soil moisture content is low, therefore it is usually applied diluted with water.
When diluted with water (at a 1:5 ratio for container-grown annual
crops with fresh growing medium each season or a 1:8 ratio for more general use), it can be applied directly to soil as a fertilizer.
The fertilization effect of urine has been found to be comparable to that of commercial nitrogen fertilizers.
Concentrations of heavy metals such as lead
, and cadmium
, commonly found in sewage sludge, are much lower in urine.
Urine can also be used safely as a source of nitrogen in carbon-rich compost
The health risks of using urine as a natural source of agricultural fertilizer are generally regarded as negligible, especially when dispersed in the soil rather than on the part of the plant that is consumed. Urine can even be distributed via perforated hoses buried some 10 cm under the surface of the soil
among crop plants, thus minimizing risk of odors, loss of nutrients, or transmission of pathogen
Given that the urea in urine breaks down into ammonia, urine has been used for cleaning. In pre-industrial times, urine was used – in the form of ''lant
'' or aged urine – as a cleaning fluid.
Urine was also used for whitening teeth in Ancient Rome
Urine was used before the development of a chemical industry
in the manufacture of gunpowder
. Urine, a nitrogen source, was used to moisten straw or other organic material, which was kept moist and allowed to rot for several months to over a year. The resulting salts
were washed from the heap with water, which was evaporated to allow collection of crude saltpeter crystals, that were usually refined before being used in making gunpowder.
The ''US Army Field Manual
'' advises ''against'' drinking urine for survival. These guides explain that drinking urine tends to worsen rather than relieve dehydration due to the salts in it, and that urine should not be consumed in a survival situation, even when there is no other fluid available. In hot weather survival situations, where other sources of water are not available, soaking cloth (a shirt for example) in urine and putting it on the head can help cool the body.
During World War I
experimented with numerous poisonous gases as weapons. After the first German chlorine
gas attacks, Allied troops were supplied with masks of cotton pads that had been soaked in urine. It was believed that the ammonia
in the pad neutralized the chlorine. These pads were held over the face until the soldiers could escape from the poisonous fumes. The Vickers machine gun
, used by the British Army during World War I, required water for cooling when fired so soldiers would resort to urine if water was unavailable.
states that urine works well against jellyfish
stings. This scenario has appeared many times in popular culture including in the ''Friends
'' episode "The One With the Jellyfish", an early episode of ''Survivor
'', as well as the films ''The Real Cancun
'' (2003), ''The Heartbreak Kid
'' (2007) and ''The Paperboy
'' (2012). However, at best it is ineffective, and in some cases this treatment may make the injury worse.
Urine has often been used as a mordant
to help prepare textiles, especially wool, for dyeing. In the Scottish Highlands and Hebrides, the process of "waulking
" (fulling) woven wool is preceded by soaking in urine, preferably infantile.
The fermentation of urine by bacteria produces a solution of ammonia
; hence fermented urine was used in Classical Antiquity
to wash cloth and clothing, to remove hair from hides in preparation for tanning, to serve as a mordant
in dying cloth, and to remove rust from iron. Ancient Romans
used fermented human urine (in the form of lant
) to cleanse grease stains from clothing.
The emperor Nero
instituted a tax ( la|vectigal urinae) on the urine industry, continued by his successor, Vespasian
. The Latin saying ''Pecunia non olet
'' (money doesn't smell) is attributed to Vespasian – said to have been his reply to a complaint from his son
about the unpleasant nature of the tax. Vespasian's name is still attached to public urinal
s in France (''vespasiennes''), Italy (''vespasiani''), and Romania (''vespasiene'').
spent much time trying to extract gold from urine, which led to discoveries such as white phosphorus
by German alchemist Hennig Brand
when distilling fermented
urine in 1669. In 1773 the French chemist Hilaire Rouelle
discovered the organic compound urea
by boiling urine dry.
Society and culture
The English word ''urine'' (, ) comes from the Latin
''urina'' (''-ae'', ''f''.), which is cognate with ancient words in various Indo-European languages
that concern water, liquid, diving, rain, and urination. The onomatopoetic
term ''piss'' was the usual word for urination before the 14th century and is now considered vulgar. ''Urinate'' was at first used mostly in medical contexts. ''Piss'' is also used in such colloquialisms as ''to piss off'', ''piss poor'', and the slang expression ''pissing down'' to mean heavy rain. Euphemism
s and expressions used between parents and children
(such as ''wee'', ''pee'', and many others) have long existed.
'' is a word for aged urine, originating from the Old English
word ''hland'' referring to urine in general.
* Drinking urine
* Urine therapy
, an attraction to urine
at the University of Utah Eccles Health Sciences Library