Depending on the fluid intake, humans produce around one to two liters of urine per day. Our excretory organs, the kidneys, produce urine. In addition to water, harmful metabolic products that are no longer required are excreted in the urine. The body filters these urinary substances out of the blood through the kidneys.
Urine is clear and its color ranges from light yellow to amber. The odor of fresh urine is neutral, but quick bacterial decomposition produces its typical pungent, ammonia-like odor. This can vary depending on your diet and fluid intake (the less you drink, the darker the urine becomes). The morning urine is usually darker than urine given during the day.
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Why is urine yellow?
Urobilin (urochrome) is responsible for the yellow color of urine. Urochrome is a metabolic product which is produced when the iron-containing pigment, hemoglobin is broken down. Urobilin is an important degradation product of hemoglobin. It is excreted with the urine via the kidneys and ensures urine’s yellow color. Urine is 95 percent water. It contains many organic and inorganic substances. For example, electrolytes, creatinine, urea, uric acid, amino acids, ketone bodies, small amounts of protein, vitamins and hormones.
Degradation products as well as toxins are removed from the body through urine. As a result it can be of different color, which in turn can be harmless or indicate illness. For example, discolored urine, with an abnormal smell and appearance, can be completely harmless, but in some cases it can indicate a disease.
What affects urine color?
The color of urine depends on both the amount of fluids we drink and our diet. Certain foods can cause the urine to look unusual. The urine is typically clear, light yellow to amber.
If you drink a lot, you are diluting your urine. It becomes light yellow to completely colorless. On the other hand, if you do not drink enough, the urine becomes more concentrated and significantly darker. This means that by adjusting liquid intake people can influence the color of their urine.
Food can also change urine color. Certain supplements, vitamin B2 for example, cause urine to become neon yellow. Eating rhubarb affects the urine depending on its pH value. If you eat the vegetable when the urine is acidic, then it turns yellow-brown. If you eat rhubarb while your urine is alkaline, it can even become pink. Consuming beetroot in large quantities can cause urine to turn red.
Why is urine sometimes light yellow?
As mentioned before, urine color is strongly dependent on fluid intake. If you drink a lot, you basically dilute your urine, rendering it light yellow.
Why is urine sometimes dark yellow?
The urine is naturally dark yellow (amber) sometimes. Dark yellow urine is common in healthy people and does not necessarily indicate a disease. Fluid intake strongly influences urine color. This means that if we drink less, the urine becomes less diluted and its color becomes darker.
Dark yellow urine often occurs in the morning or when you don’t consume enough fluid during the day. Another reason for dark yellow urine can be loss of fluids. If we sweat a lot, for example while exercising, the body tries to conserve water and excretes less fluid in order to counteract dehydration. In such cases the urine is very concentrated and dark yellow. The body behaves similarly when we lose fluids due to diarrhea or vomiting.
Is urine color an indicator of a disease?
Urine color can indicate various diseases or conditions. Very concentrated, dark yellow urine occurs when there is little fluid intake, but also with diarrhea and vomiting, i.e. gastrointestinal diseases.
If the urine is yellow-green or blue-green, there may be an infection with the bacterium Pseudomonas. These germs can cause inflammation of the heart, lungs, wounds, respiratory and urinary tract and are common in hospitals. This pathogen has a characteristic smell and color.
Red urine can have harmless causes, for example from eating a lot of beetroots or from certain medications. Blood in the urine can also cause it to appear red and must be examined by a doctor. Red-brown urine can also get its color from blood.
Blood in the urine can have a wide variety of causes. Urinary tract infections, kidney inflammation, bladder or kidney stones can be responsible for blood in urine. But also tumors (bladder, urethra or kidney cancer), injuries or foreign bodies in the urethra or vascular diseases. If the urine is brown with yellow or brown foam, there may be liver damage or blocked biliary tract.
In men, blood in the urine can indicate an inflammation of the prostate or an enlarged prostate. In women, blood in the urine can occur as part of menstrual bleeding. Blood in the urine can be harmless or indicate one of the diseases mentioned. In any case you must consult a doctor if you detect blood.
My urine is dark yellow even though I drink a lot – why?
Dark yellow urine is mainly associated with the amount of water consumed. It is said that if you drink a lot, the urine becomes clear and light yellow. If you drink less, the urine becomes more concentrated and darker. It is possible that from your own perspective, you drink a lot. Everyone needs a different amount of fluid. If your body requires more fluids, you have to drink more. It can help to try to drink more water and observe the color of the urine. It is helpful to drink water and teas instead of sweet sodas that contain coloring and preservatives.
But dark yellow urine can have other causes. Certain medications, such as some antimalarial antibiotics, produce dark yellow urine. The cause might also be a disease of the liver such as hepatitis or liver cirrhosis. But also a metabolic disorder (e.g. porphyria), Gilbert’s syndrome (GS) or jaundice.
If the urine is dark even though you are properly hydrated, you should see a doctor to rule out any possible condition.
What causes neon yellow urine?
Neon yellow, intensely bright urine is often the result of taking nutritional supplements that contain vitamin B2. This vitamin, also known as riboflavin, is commonly taken to aid digestion and metabolism of amino acids, fats, and carbohydrates. Vitamin B2 promotes energy metabolism and protein biosynthesis. Overdosing has no known consequences. Coloring of the urine is a common side effect, as riboflavin is water-soluble. These types of vitamins are carried through the bloodstream, and excesses pass out of the body in urine.