Urine

[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.

[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.

In humans, soluble wastes are excreted primarily by the urinary system and, to a lesser extent in terms of urea, removed by perspiration.

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.

[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.

[11] Urobilin is a final waste product resulting from the breakdown of heme from hemoglobin during the destruction of aging blood cells.

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.

[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.

[22] Drugs that can decrease urine pH include ammonium chloride, chlorothiazide diuretics, and methenamine mandelate.

Abdul Malik Ibn Habib of Andalusia (d. 862 AD) mentions numerous reports of urine examination throughout the Umayyad empire.

A culture of the urine is performed when a urinary tract infection is suspected, as bacteriuria without symptoms does not require treatment.

Urine contains proteins and other substances that are useful for medical therapy and are ingredients in many prescription drugs (e.g., Ureacin, Urecholine, Urowave).

[34] Urine from pregnant women contains enough human chorionic gonadotropins for commercial extraction and purification to produce hCG medication.

[citation needed] Applying urine as fertilizer has been called "closing the cycle of agricultural nutrient flows" or ecological sanitation or ecosan.

[41] Concentrations of heavy metals such as lead, mercury, and cadmium, commonly found in sewage sludge, are much lower in urine.

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.

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.

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.

After the first German chlorine gas attacks, Allied troops were supplied with masks of cotton pads that had been soaked in urine.

In the Scottish Highlands and Hebrides, the process of "waulking" (fulling) woven wool is preceded by soaking in urine, preferably infantile.

[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.

In 1773 the French chemist Hilaire Rouelle discovered the organic compound urea by boiling urine dry.

Sample of human urine
The chemical structure of urea
Urine under the microscope
Medical experts have long connected urine colour with certain medical conditions. A medieval chart showing the medical implications of different urine color
Dogs communicate using olfactory signals in urine. [ 14 ]
A Doctor Examining Urine . Trophime Bigot .
Urine of pregnant women in the first trimester is collected by a company which purifies the fertility hormone hCG from it (Ede, the Netherlands)
Urine after four months of storage (note the color and turbidity change compared to fresh human urine). During storage, the urea in urine is rapidly hydrolyzed by urease, creating ammonia. Collected urine can be used as a fertilizer.
Fresh human urine after excretion
Medieval Welsh text from the Red Book of Hergest on uroscopy , called Ansoddau'r Trwnc (the 'Qualities of Urine'). Opening lines (translated):
"Since it is through the qualities of the urine that a person's faults and his dangers and his diseases and his illness can be identified..."
Image of two facing pages of the illuminated manuscript of "Isagoge", fols. 42b and 43a. On the top of the left hand page is an illuminated letter "D" – initial of De urinarum differencia negocium ('The matter of the differences of urines'). Inside the letter is a picture of a master on bench pointing at a raised flask while lecturing on the "Book on urines" of Theophilus. The right hand page is only shown in part. On its very bottom is an illuminated letter "U" – initial of Urina ergo est colamentum sanguinis ('Urine is the filtrate of the blood'). Inside the letter is a picture of a master holding up a flask while explaining the diagnostic significance of urine to a student or a patient. HMD Collection, MS E 78.