Urine Color and its Meaning in Health and in Disease
Normal urine is pale yellow or straw-yellow in color. Urine may have a variety of other colors, however, including dark yellow, orange, pink, red, green, blue, brown and even black. These rainbow hues may be caused by dehydration, ingested foods and drinks, supplements, medications, injuries and illnesses.
If your urine has an unusual color, there's a good chance that the color change is caused by a harmless factor. Some detective work is necessary, however, to pinpoint the cause of the change. If there is no apparent cause or if the strange color continues, a doctor's advice should be sought.
Urine is produced by the kidneys from blood plasma, stored in the urinary bladder and then excreted out of the body when the bladder is full. Urine contains water, salts and wastes produced by cell activity.
Normal Urine Color
Urochrome was the first name for the yellow pigment in urine. However, many researchers now say that urobilin is responsible for urine's yellow color. Some scientists consider urochrome and urobilin to be the same chemical. Others believe that they are different substances and that both occur in urine. Urobilin is produced from the breakdown of hemoglobin, the red pigment which transports oxygen around the body in red blood cells. The hemoglobin is released when old red blood cells are destroyed.
Dehydration causes less water to enter the urine, so it appears dark yellow. Urine is usually darkest when we get up in the morning, since we’ve spent the night without drinking. Dark yellow urine during the day indicates that we’re not drinking enough water and is likely to appear if we’ve been sweating heavily without replenishing our body’s water content.
A Urine Color Chart to Check Hydration
The website of Carleton University in Ottawa, Canada, provides a urine color chart for people to check their degree of hydration. The chart can be printed, but check that your printer produces colors that match the screen colors. Note that if you've recently ingested foods, drinks, vitamins, medications or dyes that color the urine, the chart may not be accurate.
Fluorescent Yellow and Orange Urine
Vitamin B2, also called riboflavin, is yellow in color. If we eat more riboflavin than we need – which sometime happens when we take Vitamin B2 supplements – the excess riboflavin enters the urine and gives it a fluorescent yellow or neon yellow appearance.
Eating a lot of carrots can turn urine yellow or orange and can give the skin a yellow-orange color, a condition known as carotenemia. The pigment responsible for these color changes is beta-carotene. Vitamin C can also color urine dark yellow or orange. Warfarin (brand name Coumadin) is an anticoagulant and is one medication that causes urine to appear orange. Rifampin, an antibiotic, has a similar effect.
Pink or Red Urine
Pink or red urine may be caused by eating beets, blackberries or rhubarb or by taking certain medications. More seriously, the red color may develop due to lead or mercury poisoning or due to unusual bleeding that is not part of menstruation.
Urine may sometimes contain red blood cells or hemoglobin released from damaged red blood cells. It may also contain myoglobin. Myoglobin is a red pigment that stores oxygen in muscles. Damaged muscle cells may release myoglobin, turning the urine red. Blood in the urine could indicate an injured kidney, urinary bladder or urinary tract.
In females, the openings from the gastrointestinal tract, urinary tract and reproductive tract are close together, so sometimes medical tests are needed to discover where blood in the urine is coming from.
Urine can turn pink after taking laxatives containing a substance called phenolphthalein. Phenolphthalein turns pink when it’s in alkaline urine. Some countries have banned phenolphthalein in laxatives, since at high doses the chemical has been found to cause cancer in lab animals.
Phenazopyridine (trade name Pyridium) is a medication that acts as an anesthetic in the urinary tract. It's prescribed for urinary tract infections and injuries and after medical tests or surgery on the tract. One of the medication's side effects is the production of an orange-red urine.
Green or Blue Urine
Eating a lot of asparagus can sometimes turn urine green and may also give the urine a distinct odor. An infection by a bacterium called Pseudomonas aeruginosa can cause urine to turn green or blue.
Several medications may cause blue urine. These include amitriptyline, an antidepressant; indomethacin (trade name Indocin), a non-steroidal anti-inflammatory drug; cimetidine (trade name Tagamet), a stomach acid reducer; and promethazine (trade name Phenergan), an anti-nausea drug. Urised, which is used to treat urinary tract pain, contains a dye called methylene blue which colors the urine.
Metabolic disorders can also produce blue urine. Indicanuria is a condition in which the body cannot absorb the amino acid tryptophan from the intestine. Intestinal bacteria break the tryptophan down into chemicals that are excreted in the urine and cause it to appear blue. In babies, the disorder is sometimes called “blue diaper syndrome.” Familial hypercalcemia, an inherited disorder in which the level of calcium in the body is elevated, can also cause blue diaper syndrome.
Brown or Black Urine
Eating lots of aloe or fava beans (also called broad beans) can result in brown urine. Taking cascara and senna laxatives can produce the same effect. Methyldopa (brand name Aldomet), a drug given to help high blood pressure, can cause urine to turn black when it mixes with bleach in the toilet bowl. The antibiotic metronidazole darkens urine.
Alkaptonuria (also spelled alcaptonuria) is an inherited condition in which urine becomes brown-black when it's exposed to air. In this disorder a person cannot completely break down two amino acids called phenylalanine and tyrosine. As a result, a substance called homogentisic acid collects in the body and is deposited in the urine. The urine appears black when the acid reacts with air.
Liver diseases such as hepatitis and cirrhosis, kidney disease and kidney stones can all produce dark brown urine. Dark urine is also a symptom of some types of cancer.
Porphyria and Urine Color
People with porphyria may have red-purple or red-brown urine. The illness develops when someone lacks a specific enzyme or enzymes involved in the production of heme, the red, iron-containing part of the hemoglobin molecule. Heme belongs to the group of chemicals known as porphyrins, which are often intensely colored.
Heme is produced in a series of eight steps. Each step is controlled by a specific enzyme. At each step in the process a new porphyrin precursor molecule is made, which is then converted to a different precursor in the next step. In people with porphyria one or more of the enzymes involved in heme production are missing. This means that a porphyrin precursor can’t be changed into the next precursor in the chain or into heme. The precursors may build up in the body and reach a toxic level. They collect in the skin, the organs, the feces and the urine. The porphyrin precursor molecules are colorless, but when urine is exposed to light the molecules are converted into colored porphyrins.
Acute Intermittent Porphyria (AIP)
Types of Porphyria
There are at least eight types of porphyria. Some types affect the skin, causing blisters, swelling and itching when the skin is exposed to sunlight. Other forms affect the internal organs, nervous system and brain, causing symptoms such as pain, cramping, vomiting, numbness, paralysis, personality changes and mental disorders.
King George III of Britain, who was known as the “mad” king, exhibited periods of body pain, paralysis and insanity. His doctors recorded the fact that he had dark red or purple urine on several occasions. Today’s researchers believe that King George probably suffered from a form of porphyria.
Porphyria is caused by a genetic problem. Sometimes the disorder is inactive and only becomes active when a person is exposed to a stress of some kind. Doctors today have several ways to treat porphyria.
Useful Porphyria Links
The most common cause of cloudy urine is the presence of phosphate crystals in the urine. These crystals can appear after eating or drinking high-phosphate foods, such as milk. The phosphate crystals will disappear if a small quantity of vinegar is added to the urine.
Cloudy urine may sometimes be a sign of a urinary tract infection, which causes white blood cells to collect in the urine. White blood cells fight invading bacteria and viruses. The urinary tract infection may be accompanied by other symptoms, such as a frequent need to urinate and a burning sensation during urination.
A disorder called proteinuria can also produce cloudy urine. In this condition protein builds up in the urine. Proteinuria is sometimes temporary and disappears without treatment, but it may indicate kidney damage. It can also be a symptom of certain diseases, such as diabetes and hypertension (high blood pressure). Proteinuria may develop in pregnant women who are suffering from preeclampsia. This is a condition in which a woman develops high blood pressure and a high protein level in her urine during pregnancy.
Diabetes insipidus is a condition caused by a problem involving antidiuretic hormone or ADH. It's not the same condition as diabetes mellitus, which is caused by a problem involving insulin.
Urine that looks like pure water, with no yellow color, may indicate that a person is well hydrated or even over–hydrated. Drinking too much water can be dangerous, since it dilutes essential electrolytes inside the body.
Large amounts of colorless urine may be a symptom of diabetes insipidus, which is not the same condition as diabetes mellitus. In diabetes mellitus (which is commonly broken down into Type 1 diabetes, Type 2 diabetes and gestational diabetes), a person doesn’t make enough insulin or their cells don’t respond to insulin properly. Insulin is a hormone made by the pancreas that increases the permeability of cell membranes to glucose, the sugar that travels in blood. Insulin allows glucose to leave the blood and enter the cells. Diabetes mellitus is sometimes called “sugar diabetes”, since glucose collects in the blood of an untreated diabetic.
In diabetes insipidus, the body doesn’t produce enough antidiuretic hormone (also known as ADH and vasopressin), or the kidneys don't respond to the hormone properly. ADH is made by the hypothalamus in the brain and stored in the posterior pituitary gland until it's needed. The hormone stimulates the kidneys to send water back into the tissues and bloodstream so that it isn't excreted in the urine. Without ADH, too much urine is produced and the person is constantly thirsty. Diabetes insipidus is sometimes called “water diabetes.”
A Nurse Describes Diabetes Insipidus Symptoms
More Information About Diabetes Insipidus
- Diabetes insipidus at the National Health Service
Although diabetes insipidus and diabetes mellitus are unrelated diseases, they both have increased thirst and urination as symptoms. These symptoms should always be investigated by a doctor.
Investigating Colored Urine
Colored urine may indicate a medical problem or may be the result of ingesting certain foods, drinks, medications or multivitamins containing pigments or added dyes. Diagnostic dyes used in medical tests and medications can also color urine. It’s a good idea to check the information sheet that accompanies a prescribed medication or medical treatment so that you won’t be surprised by colored urine if this is one of the side effects.
It's important to discover why urine has changed color. Unless a change in color can be related to diet or a medical treatment and quickly disappears once the food or treatment is stopped, a doctor should be consulted.
© 2010 Linda Crampton
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