the Importance of Urine

Urine is one of the ways the body removes toxins and unwanted substances from the body. The kidneys work to remove excess water from the bloodstream, along with waste products from other areas of the body, and other substances that may include some medications.

The color of urine can fluctuate through the day. The first urine after waking in the morning is often the darkest and most concentrated, with urine lightening in color after the person begins to drink fluids through the day.

Urine As a Way to Measure Hydration

Urine is mostly water. In fact, urine is typically around 95 percent water with the rest being minerals, uric acid, vitamins, enzymes, and a bile acid called urobilin that gives urine its yellow color. Urine color is a reliable way to determine if enough water is being taken in during the course of a day. Straw or nearly colorless means adequate hydration while darker yellow often means that the person is mildly dehydrated.

What Normal Urine Looks Like

Normal urine is clear with a slight tint of yellow, often referred to as "straw colored." How much yellow color is present fluctuates with the amount of water in the body. A person who is well-hydrated and drinks six to eight glasses of water per day typically has light yellow urine.  A person who drinks less water than they should may have a darker yellow urine.

A normal individual may use the bathroom six or more times a day, depending on how much water they drink during the course of the day.

 More water intake usually means more trips to the bathroom.

There are many reasons that the color of the urine may change, or that the odor associated with urination may be different than what is typical.  Many causes of a change in urine color are common and not indicative of anything serious, although it can be shocking to see strangely colored urine if you do not expect it.

Signs of Urinary Tract Infection

When people start to worry about how their urine looks or smells, they are typically concerned that they may have a urinary tract infection or UTI. A urinary tract infection is an infection affecting the kidneys, ureters, bladder, or urethra. It may be present in one location, or it may be in more than one area of the urinary tract.

It is absolutely possible to have unusual looking or smelling urine without infection being present, just as it is possible to have a urinary tract infection with no symptoms. A urinalysis is the test used to examine the color and content of urine and can determine if an infection is present.

Typical urinary tract infections include one or more of the following:

• Urinary frequency: The need to go to the bathroom more frequently than usual
• Foul smelling urine: A foul odor is sometimes present with this type of infection.
• Painful urination: Burning during urination and sometimes after urination may signal the presence of irritation or infection.
• Hesitancy: Difficulty starting the flow of urine when trying to urinate
• Cloudy urine: A urinary tract infection can cause urine to look cloudy rather than clear.
• Bladder pressure or pain: Some individuals experience pressure or pain from the bladder, which is a few inches below the belly button, when they have an infection.

• Back pain: Pyelonephritis, known more commonly as a kidney infection, can cause back pain in the area over the kidneys.
• Fever: An elevated temperature is common during a urinary tract infection, but not always present.
• Fatigue: Having any infection in the body can lead to a fever.
• Delirium: Some people, especially older adults, can experience severe and sudden changes in their ability to think when a urinary tract infection is present. This confusion typically resolves when the infection is treated effectively, but it may take days to improve.
• Sepsis: An untreated urinary tract infection can turn into a more serious systemic infection that moves into the blood called sepsis. This is also referred to as urosepsis and requires antibiotic treatment, often via IV.

Unusual Urine Appearance

Cloudy Urine: Urine can be cloudy due to sediment in the urine, from holding the urine too long before going to the bathroom, prostate problems, sexually transmitted disease such as gonorrhea, and prostate enlargement. Infection may also result in the presence of white or red blood cells and pus which can also cause clouding. Kidney stones can also be responsible for foamy urine.

Foamy Urine: Urine that appears foamy, or bubbly, is typically the result of a very forceful urine stream. That may mean "pushing" harder than usual to make urine flow, or even elevated blood pressure. If it persists over time you might want to have a urinalysis test. Foamy urine can also be a sign of elevated protein in the urine—which can be a sign of a kidney problem.

Urine Odor: There are many reasons that urine may have an odor. Dehydration makes urine stronger, which can result in an increase in odor. Certain foods, such as asparagus, can make urine smell. There are also conditions that can result in unusual urine odor, such as maple syrup urine disease (MSUD) that causes the urine to smell like pancake syrup. The following are some conditions associated with particular urine odors:

• Sweet smelling urine may indicate diabetes.
• Musty smelling urine is often the result of liver disease or liver failure.
• Foul smelling urine is usually associated with the presence of a urinary tract infection.

In general, urine odor should be concerning if it persists without explanation or if it is foul in nature. If it is food-related or due to dehydration, it should pass over the course of the day as you drink water and the urine returns to normal.

Blue/Green Urine: This is most frequently caused by the presence of food dye. Strongly colored foods, such as dark blue frosting, can result in a urine color change, as can asparagus.  Green urine can also indicate the presence of pseudomonas bacteria, a very rare condition called porphyria, or dyes used for medical testing.

Some medications, including Propofol, Tagamet, methylene blue, amitriptyline, and Indocin, are known to cause a green-blue urine color. There is a rare inherited condition that increases calcium levels and can cause blue urine, it is commonly known as "blue diaper syndrome."

Amber or Brown Urine: The most common cause of dark urine is dehydration, with urine darkening as dehydration worsens, but this color can also be the result of kidney disease or liver disease. Rhabdomyolysis, a condition that results from muscle damage, can also darken urine that is often referred to as "tea colored."

Fava beans and rhubarb can also cause darkened urine.

When the liver is too sick to do its job removing bilirubin from the bloodstream, the kidneys may help with the process. Bilirubin is typically removed from the body in stool and is the reason stool is brown. When the kidneys help remove bilirubin from the body, the urine is also a shade of brown.

Orange Urine: The most common cause of orange urine is a medication called Pyridium. Also known as Azo in its over the counter formulation, Pyridium is used to reduce the symptoms of urinary tract infections. Carrots, other bright orange foods and vitamin C can also result in orange urine.

Pink/Red Urine: Pink urine can often be blamed on food intake. Beets in particular are known to cause urine output that ranges from pink to red in color. Blackberries and rhubarb can also produce this effect. The tuberculosis medication Rifampin and senna, a stool softener, can also result in pink or red urine.

Blood in the urine can cause a change in urine colors ranging from pink to dark red. A very small amount of blood can change the color of the urine, but blood in the urine can also be a sign of a significant problem with the urinary tract. If there is no clear explanation for why blood may be present in the urine, such as a menstrual period, medical attention should be sought.

Bright Yellow: B12 vitamins are known to cause a bright or highlighter yellow urine color, beta carotene (foods such as carrots) can also cause this result.

Purple: There is a very rare condition called purple urine bag syndrome, that, as you might imagine, is typically found in people who have a foley catheter to assist with urine drainage and collection. Oddly enough, the purple urine only happens when a patient has highly alkaline urine and a catheter in place. The urine doesn't actually change in color, it only appears purple in the collecting bag and if the catheter and collecting bag are changed, the urine again appears its normal color.

Porphyria, a very rare condition, can also result in a purple color.

White urine: Chyluria, or white urine, is typically caused by lymphatic fluid mixing with urine. It can also be caused by a filarial infestation, a type of parasitic disease.

Black urine: The medications Macrobid, Flagyl and Robaxin are all known to cause black urine. The sweetener/laxative sorbitol can also result in black urine. Iron injections, used to treat certain types of anemia, can also lead to urine being black.

Black urine disease, also known as alkaptonuria, is a rare condition where the body cannot process specific amino acids.

Fluorescence: In adults this is a hallmark of ethylene glycol (antifreeze) poisoning and typically only lasts for a few hours after the poisoning. Under a black light, the urine of someone poisoned with antifreeze will glow blue if the sample is obtained in the first four hours after poisoning. In children it can be suggestive of antifreeze poisoning, but, oddly enough, may be found in perfectly healthy children and should not be used alone to diagnose poisoning in younger patients.