What your urine color can tell you
Q: What causes urine to have different colors?
A: If a person is well hydrated, the normal color of urine is a pale yellow. Someone who drinks large amounts of fluid or takes diuretics (water pills) can have almost clear-looking urine. A dark yellow color may indicate a need to increase your fluid intake.
Red urine usually raises an alarm. But before you get too worried, pause to consider what you recently ate. Beets, blackberries and rhubarb can temporarily turn urine pink or red, which may be mistaken for blood. The phenomenon — dubbed “beeturia” — occurs in only about 10% to 14% of the population. Similarly, some drugs, such as senna used for constipation and the antibiotic rifampin, can give urine a red color.
If you can’t definitely attribute red urine to food or a medication, then see your doctor. He or she will use a dipstick test to confirm the presence of hemoglobin, the compound in red blood cells that carries oxygen. Most often a positive test means there are red cells in the urine, a condition called hematuria. Common causes include bladder infections and kidney stones. Usually, people with bladder infections have other symptoms, such as painful urination and a frequent urge to empty the bladder.
Kidney stones sometimes cause bloody urine, but most often there also is back or flank pain (pain in one side of the body between the upper abdomen and the back), which can be severe. Bloody urine without other symptoms might be due to a bladder or kidney tumor, or injury to the back or abdomen.
Less commonly, the dipstick test for hemoglobin is positive because red cells in the bloodstream have been attacked with antibodies or otherwise damaged. This causes them to release hemoglobin into the blood, which then gets excreted by the kidneys.
Brown or cola-colored urine also should prompt a doctor’s visit. This color change often happens when there is bilirubin in the urine. Bilirubin is a breakdown product of old hemoglobin and related compounds. Normally, the liver processes bilirubin and sends it to the bile duct. From there, it goes into the small intestine or gets stored in the gallbladder.
When the liver is inflamed or damaged or the bile duct is blocked, bilirubin can’t get out of the liver, and the bilirubin blood level increases. The kidneys then become the main way excess bilirubin leaves the body. The most common reasons for having enough bilirubin to turn urine brown are liver disease (such as hepatitis or cirrhosis) or a blocked bile duct from a gallstone.
(Howard LeWine, M.D. is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)