Urine is a liquid by-product of metabolism in humans and in many other animals. In placental mammals, urine flows from the kidneys through the ureters to the urinary bladder and exits the urethra through the penis or vulva during urination. In other vertebrates, urine is excreted through the cloaca. [1]
Urine contains water-soluble by-products of cellular metabolism that are rich in nitrogen and must be cleared from the bloodstream, such as urea, uric acid, and creatinine. A urinalysis can detect nitrogenous wastes of the mammalian body.
Urine plays an important role in the earth's nitrogen cycle. In balanced ecosystems, urine fertilizes the soil and thus helps plants to grow. Therefore, urine can be used as a fertilizer. Some animals use it to mark their territories. [2] [3] Historically, aged or fermented urine (known as lant) was also used for gunpowder production, household cleaning, tanning of leather and dyeing of textiles.
Human urine and feces are collectively referred to as human waste or human excreta, and are managed via sanitation systems. Livestock urine and feces also require proper management if the livestock population density is high.
Most animals have excretory systems 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. [4] In placental mammals, the urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The system produces urine by a process of filtration, reabsorption, 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 through the urinary meatus.
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. [5] Smaller species, including rodents and bats, cannot produce steady streams of urine and instead urinate with a series of drops. [5]
Average urine production in adult humans is around 1.4 L (0.31 imp gal; 0.37 US gal) of urine per person per day with a normal range of 0.6 to 2.6 L (0.13 to 0.57 imp gal; 0.16 to 0.69 US gal) 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. [6] 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. [6] The remainder can be broadly characterized into inorganic salts, urea, organic compounds, and organic ammonium salts. [6] [7] Urine also contains proteins, hormones, and a wide range of metabolites, [8] varying by what is introduced into the body.[ citation needed ]
The total solids in urine are on average 59 g (2.1 oz) per day per person. [8] Urea is the largest constituent of the solids, constituting more than 50% of the total. The daily volume and composition of urine varies per person based on the amount of physical exertion, environmental conditions, as well as water, salt, and protein intakes. [6] In healthy persons, urine contains very little protein and an excess is suggestive of illness, as with sugar. [8] Organic matter, in healthy persons, also is reported to at most 1.7 times more matter than minerals. [7] However, any more than that is suggestive of illness. [7]
Parameter | Value |
---|---|
pH | 6.2 |
Total nitrogen | 8830 mg/L |
Ammonium/ammonia-N | 460 mg/L |
Nitrate and nitrite | 0.06 mg/L |
Chemical oxygen demand | 6000 mg/L |
Total phosphorus | 800 – 2000 mg/L |
Potassium | 2740 mg/L |
Sulphate | 1500 mg/L |
Sodium | 3450 mg/L |
Magnesium | 120 mg/L |
Chloride | 4970 mg/L |
Calcium | 230 mg/L |
However, it is important to note that lesser amounts and concentrations of other compounds and ions are often present in urination of humans. [8]
Urine varies in appearance, depending principally upon a body's level of hydration, interactions with drugs, compounds and pigments or dyes found in food, or diseases. [8] Normally, urine is a transparent solution ranging from colorless to amber, but is usually a pale yellow. [8] Usually urination color comes primarily from the presence of urobilin. [11] Urobilin is a final waste product resulting from the breakdown of heme from hemoglobin during the destruction of aging blood cells. [12] [13]
Colorless urine indicates over-hydration. Colorless urine in drug tests can suggest an attempt to avoid detection of illicit drugs in the bloodstream through over-hydration.
Sometime after leaving the body, urine may acquire a strong "fish-like" odor because of contamination with bacteria that break down urea into ammonia.[ citation needed ] This odor is not present in fresh urine of healthy individuals; its presence may be a sign of a urinary tract infection.[ citation needed ]
The odor of normal human urine can reflect what has been consumed or specific diseases. [8] 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.[ citation needed ] Additionally, the presence of amino acids in urine (diagnosed as maple syrup urine disease) can cause it to smell of maple syrup. [15]
Eating asparagus can cause a strong odor reminiscent of the vegetable caused by the body's breakdown of asparagusic acid. [16] Likewise consumption of saffron, alcohol, coffee, tuna fish, and onion can result in telltale scents. [17] Particularly spicy foods can have a similar effect, as their compounds pass through the kidneys without being fully broken down before exiting the body. [18] [19]
The pH normally is within the range of 5.5 to 7 with an average of 6.2. [6] In persons with hyperuricosuria, acidic urine can contribute to the formation of stones of uric acid in the kidneys, ureters, or bladder. [20] Urine pH can be monitored by a physician or at home. [21]
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. [6]
Cranberries, popularly thought to decrease the pH of urine, have actually been shown not to acidify urine. [22] Drugs that can decrease urine pH include ammonium chloride, chlorothiazide diuretics, and methenamine mandelate. [23] [24]
Human urine has a specific gravity of 1.003–1.035. [6]
Urine is not sterile, not even in the bladder. [25] [26] In the urethra, epithelial cells lining the urethra are colonized by facultatively anaerobic Gram-negative rod and cocci bacteria. [27] One study conducted in Nigeria isolated a total of 77 distinct bacterial strains from 100 healthy children (ages 5–11) as well as 39 strains from 33 cow urine samples, a considerable amount being pathogens. [28] Pathogens identified and their percentages were:
Humans aged 5–11 | Bacterial percentage in humans | Bacterial percentage in cows |
---|---|---|
Bacillus | 10.4% | 5.1% |
Staphylococcus | 2.6% | 2.6% |
Citrobacter | 3.9% | 12.8% |
Klebsiella | 7.8% | 12.8% |
Escherichia coli | 36.4% | 23.1% |
Proteus | 18.2% | 23.1% |
Pseudomonas | 9.1% | 2.6% |
Salmonella | 3.9% | 5.1% |
Shigella | 7.8% | 12.8% |
The study also states:
Multiple antibiotic resistance (MAR) rates recorded in children urinal bacterial species were 37.5–100% (Gram-positive) and 12.5–100% (Gram-negative), while MAR among the cow urinal bacteria was 12.5–75.0% (Gram-positive) and 25.0–100% (Gram-negative).
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. [29] Diabetes mellitus got its name because the urine is plentiful and sweet. [30] The name uroscopy refers to any visual examination of the urine, [31] including microscopy, although it often refers to the aforementioned prescientific or Proto-scientific forms of urine examination. Clinical urine tests today duly note the 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 bacteriuria without symptoms does not require treatment. [32] 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.
Urine contains proteins and other substances that are useful for medical therapy and are ingredients in many prescription drugs (e.g., Ureacin, Urecholine, Urowave).[ citation needed ] Urine from postmenopausal women is rich in gonadotropins that can yield follicle stimulating hormone and luteinizing hormone for fertility therapy. [33] One such commercial product is Pergonal. [34]
Urine from pregnant women contains enough human chorionic gonadotropins for commercial extraction and purification to produce hCG medication. Pregnant mare urine is the source of estrogens, namely Premarin. [33] Urine also contains antibodies, which can be used in diagnostic antibody tests for a range of pathogens, including HIV-1. [35]
Urine can also be used to produce urokinase, which is used clinically as a thrombolytic agent.[ citation needed ]
Applying urine as fertilizer has been called "closing the cycle of agricultural nutrient flows" or ecological sanitation or ecosan. Urine fertilizer is usually applied diluted with water because undiluted urine can chemically burn the leaves or roots of some plants, causing plant injury, [36] particularly if the soil moisture content is low. The dilution also helps to reduce odor development following application. 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. [37] [38] The fertilization effect of urine has been found to be comparable to that of commercial nitrogen fertilizers. [39] [40] Urine may contain pharmaceutical residues (environmental persistent pharmaceutical pollutants). [41] Concentrations of heavy metals such as lead, mercury, and cadmium, commonly found in sewage sludge, are much lower in urine. [42]
Typical design values for nutrients excreted with urine are: 4 kg nitrogen per person per year, 0.36 kg phosphorus per person per year and 1.0 kg potassium per person per year. [43] : 5 Based on the quantity of 1.5 L urine per day (or 550 L per year), the concentration values of macronutrients as follows: 7.3 g/L N; .67 g/L P; 1.8 g/L K. [43] : 5 [44] : 11 These are design values but the actual values vary with diet. [45] [a] Urine's nutrient content, when expressed with the international fertilizer convention of N:P2O5:K2O, is approximately 7:1.5:2.2. [44] [b] Since urine is rather diluted as a fertilizer compared to dry manufactured nitrogen fertilizers such as diammonium phosphate, the relative transport costs for urine are high as a lot of water needs to be transported. [44]
The general limitations to using urine as fertilizer depend mainly on the potential for buildup of excess nitrogen (due to the high ratio of that macronutrient), [37] and inorganic salts such as sodium chloride, which are also part of the wastes excreted by the renal system. Over-fertilization with urine or other nitrogen fertilizers can result in too much ammonia for plants to absorb, acidic conditions, or other phytotoxicity. [41] Important parameters to consider while fertilizing with urine include salinity tolerance of the plant, soil composition, addition of other fertilizing compounds, and quantity of rainfall or other irrigation. [47] It was reported in 1995 that urine nitrogen gaseous losses were relatively high and plant uptake lower than with labelled ammonium nitrate.[ citation needed ] In contrast, phosphorus was utilized at a higher rate than soluble phosphate. [48] Urine can also be used safely as a source of nitrogen in carbon-rich compost. [38]Given that 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. [49] Urine was also used for whitening teeth in Ancient Rome. [50]
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. [51]
Urophagia is the consumption of urine . Urine was used in several ancient cultures for various health, healing, and cosmetic purposes; urine drinking is still practiced today. In extreme cases, people may drink urine if no other fluids are available, although numerous credible sources (including the US Army Field Manual ) advise against using it. Urine may also be consumed as a sexual activity . ( Full article... )
The US Army Field Manual advises against drinking urine for survival. The manual explains 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. [52]
During World War I, Germans 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.[ citation needed ]
Urban legend states that urine works well against jellyfish stings. [53] 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. [54] [55] [56]
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. [57]
Urine plays a role in olfactory communication, since it contains semiochemicals that act as pheromones. [58] [59] The urine of predator species often contains kairomones [60] that serve as a repellent against their prey species. [61]
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. [62] Ancient Romans used fermented human urine (in the form of lant) to cleanse grease stains from clothing. [63] The emperor Nero instituted a tax (Latin : vectigal urinae) on the urine industry, continued by his successor, Vespasian. The Latin saying Pecunia non olet ('money does not 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 urinals in France (vespasiennes), Italy (vespasiani), and Romania (vespasiene).
Alchemists 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.
The English word urine ( /ˈjuːrɪn/ , /ˈjɜːrɪn/ ) 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 (for example Sanskrit varṣati meaning 'it rains' or vār meaning 'water' and Greek ourein meaning 'to urinate'). [64] The onomatopoetic term piss predates the word urine, but is now considered vulgar. [65] [66] Urinate was at first used mostly in medical contexts.[ citation needed ]Piss is also used in such colloquialisms as to piss off, [65] piss poor, and the slang expression pissing down to mean heavy rain. Euphemisms and expressions used between parents and children (such as wee, pee, and many others) have long existed.
Lant is a word for aged urine, originating from the Old English word hland referring to urine in general.
Urea, also called carbamide, is an organic compound with chemical formula CO(NH2)2. This amide has two amino groups joined by a carbonyl functional group. It is thus the simplest amide of carbamic acid.
A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Many sources of fertilizer exist, both natural and industrially produced. For most modern agricultural practices, fertilization focuses on three main macro nutrients: nitrogen (N), phosphorus (P), and potassium (K) with occasional addition of supplements like rock flour for micronutrients. Farmers apply these fertilizers in a variety of ways: through dry or pelletized or liquid application processes, using large agricultural equipment, or hand-tool methods.
Kidney stone disease, also known as renal calculus disease, nephrolithiasis or urolithiasis, is a crystallopathy where a solid piece of material develops in the urinary tract. Renal calculi typically form in the kidney and leave the body in the urine stream. A small calculus may pass without causing symptoms. If a stone grows to more than 5 millimeters, it can cause blockage of the ureter, resulting in sharp and severe pain in the lower back that often radiates downward to the groin. A calculus may also result in blood in the urine, vomiting, or painful urination. About half of people who have had a renal calculus are likely to have another within ten years.
Azotemia, also spelled azotaemia, is a medical condition characterized by abnormally high levels of nitrogen-containing compounds in the blood. It is largely related to insufficient or dysfunctional filtering of blood by the kidneys. It can lead to uremia and acute kidney injury if not controlled.
The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine. The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled through the urethra during urination. The female and male urinary system are very similar, differing only in the length of the urethra.
The excretory system is a passive biological system that removes excess, unnecessary materials from the body fluids of an organism, so as to help maintain internal chemical homeostasis and prevent damage to the body. The dual function of excretory systems is the elimination of the waste products of metabolism and to drain the body of used up and broken down components in a liquid and gaseous state. In humans and other amniotes, most of these substances leave the body as urine and to some degree exhalation, mammals also expel them through sweating.
Urination is the release of urine from the bladder to the outside of the body. Urine is released through the urethra and exits the penis or vulva through the urinary meatus in placental mammals, but is released through the cloaca in other vertebrates. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, or, rarely, emiction, and known colloquially by various names including peeing, weeing, pissing, and euphemistically number one. The process of urination is under voluntary control in healthy humans and other animals, but may occur as a reflex in infants, some elderly individuals, and those with neurological injury. It is normal for adult humans to urinate up to seven times during the day.
Ureases, functionally, belong to the superfamily of amidohydrolases and phosphotriesterases. Ureases are found in numerous bacteria, fungi, algae, plants, and some invertebrates, as well as in soils, as a soil enzyme. They are nickel-containing metalloenzymes of high molecular weight.
Excretion is elimination of metabolic waste, which is an essential process in all organisms. In vertebrates, this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. For example, placental mammals expel urine from the bladder through the urethra, which is part of the excretory system. Unicellular organisms discharge waste products directly through the surface of the cell.
Hyperammonemia, or high ammonia levels, is a metabolic disturbance characterised by an excess of ammonia in the blood. Severe hyperammonemia is a dangerous condition that may lead to brain injury and death. It may be primary or secondary.
Melamine is an organic compound with the formula C3H6N6. This white solid is a trimer of cyanamide, with a 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass, and its derivatives have fire-retardant properties due to its release of nitrogen gas when burned or charred. Melamine can be combined with formaldehyde and other agents to produce melamine resins. Such resins are characteristically durable thermosetting plastic used in high pressure decorative laminates such as Formica, melamine dinnerware including cooking utensils, plates, plastic products, laminate flooring, and dry erase boards. Melamine foam is used as insulation, soundproofing material and in polymeric cleaning products, such as Magic Eraser.
A urine test is any medical test performed on a urine specimen. The analysis of urine is a valuable diagnostic tool because its composition reflects the functioning of many body systems, particularly the kidneys and urinary system, and specimens are easy to obtain. Common urine tests include the routine urinalysis, which examines the physical, chemical, and microscopic properties of the urine; urine drug screening; and urine pregnancy testing.
Organic fertilizers are fertilizers that are naturally produced. Fertilizers are materials that can be added to soil or plants, in order to provide nutrients and sustain growth. Typical organic fertilizers include all animal waste including meat processing waste, manure, slurry, and guano; plus plant based fertilizers such as compost; and biosolids. Inorganic "organic fertilizers" include minerals and ash. Organic refers to the Principles of Organic Agriculture, which determines whether a fertilizer can be used for commercial organic agriculture, not whether the fertilizer consists of organic compounds.
Struvite (magnesium ammonium phosphate) is a phosphate mineral with formula: NH4MgPO4·6H2O. Struvite crystallizes in the orthorhombic system as white to yellowish or brownish-white pyramidal crystals or in platy mica-like forms. It is a soft mineral with Mohs hardness of 1.5 to 2 and has a low specific gravity of 1.7. It is sparingly soluble in neutral and alkaline conditions, but readily soluble in acid.
Metabolic wastes or excrements are substances left over from metabolic processes (such as cellular respiration) which cannot be used by the organism (they are surplus or toxic), and must therefore be excreted. This includes nitrogen compounds, water, CO2, phosphates, sulphates, etc. Animals treat these compounds as excretes. Plants have metabolic pathways which transforms some of them (primarily the oxygen compounds) into useful substances.
Sodium phenylbutyrate, sold under the brand name Buphenyl among others, is a salt of an aromatic fatty acid, 4-phenylbutyrate (4-PBA) or 4-phenylbutyric acid. The compound is used to treat urea cycle disorders, because its metabolites offer an alternative pathway to the urea cycle to allow excretion of excess nitrogen.
In medicine, the urea-to-creatinine ratio (UCR), known in the United States as BUN-to-creatinine ratio, is the ratio of the blood levels of urea (BUN) (mmol/L) and creatinine (Cr) (μmol/L). BUN only reflects the nitrogen content of urea and urea measurement reflects the whole of the molecule, urea is just over twice BUN. In the United States, both quantities are given in mg/dL The ratio may be used to determine the cause of acute kidney injury or dehydration.
Phenylacetylglutamine is a product formed by the conjugation of phenylacetate and glutamine. It is a common metabolite that occurs naturally in human urine.
Reuse of human excreta is the safe, beneficial use of treated human excreta after applying suitable treatment steps and risk management approaches that are customized for the intended reuse application. Beneficial uses of the treated excreta may focus on using the plant-available nutrients that are contained in the treated excreta. They may also make use of the organic matter and energy contained in the excreta. To a lesser extent, reuse of the excreta's water content might also take place, although this is better known as water reclamation from municipal wastewater. The intended reuse applications for the nutrient content may include: soil conditioner or fertilizer in agriculture or horticultural activities. Other reuse applications, which focus more on the organic matter content of the excreta, include use as a fuel source or as an energy source in the form of biogas.
Anthroponics is a type of hydroponics system that uses human waste like urine as the source of nutrients for the cultivated plants. In general, the human urine or mixed waste is collected and stored for a period of time, before being applied either directly or passed through a biofilter before reaching the plants. As a form of organic hydroponics, anthroponics combines elements of both hydroponics and aquaponics systems.
Likewise consumption of saffron, alcohol, coffee, tuna fish, and onion can result in telltale scents.
We did not find evidence that urinary acidification was responsible for the observed effect, since the median pH of urine samples in the cranberry group (6.0) was actually higher than that in the experimental group (5.5). While cranberry juice has been advocated as a urinary acidifier to prevent urinary tract infections, not all studies have shown a reduction in urine pH with cranberry juice ingestion, even with consumption of 2000 mL per day.
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: CS1 maint: location missing publisher (link)Minimize odors by adding white vinegar or citric acid to the urine collection container before any urine is added. We use 1-2 cups of white vinegar or 1 tablespoon of citric acid per 5-gallon container. Adding vinegar also helps reduce nitrogen loss (via ammonia volatilization) during short-term storage.