Stool Color and Texture Changes
(Black, Red, Maroon, Green, Yellow, Gray, Tarry, Sticky)
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
- What color is normal stool?
- What causes normal stool color?
- How do changes in bilirubin affect stool color?
- How does intestinal bleeding change stool color?
- What other things can cause changes in the color of stool?
- What are the symptoms of stool color changes?
- Patient Comments: Stool Color & Texture Changes - Personal Experience
- Find a local Gastroenterologist in your town
What color is normal stool?
Stool (feces) is most commonly brown in color, and many people become curious or concerned when the color of their stool changes. Most stool-to-stool changes in color have little meaning; however, some changes, particularly if the changes are consistent from stool-to-stool and not present in only one stool, can be important.
What causes normal stool color?
The color of stool is normally due to the presence of bile, specifically, the bilirubin in bile. Bilirubin is formed from hemoglobin after hemoglobin is released from red blood cells during their destruction, a part of the normal process of replacing the red blood cells in blood. The released hemoglobin is modified chemically and removed from the blood by the liver. In the liver the chemically changed hemoglobin (called bilirubin) is attached to other chemicals and secreted from the cells of the liver into bile. Depending on the concentration of bilirubin, bile can vary from almost black to light yellow in color.
How do changes in bilirubin affect stool color?
Bilirubin travels with bile that is produced by the liver and then transported out of the liver by the bile ducts into the gallbladder, where it is stored until it is released into the intestines. (Bile is an important way for the liver to get rid of waste products such as bilirubin that are formed within the body.) As the bile and bilirubin pass through the intestines they are exposed to bacteria within the intestines. The bacteria can change the chemical nature of bilirubin, and this can change the color of stool.
If stool travels through the intestines at a normal speed, its color is a normal brown. Travel at a more rapid speed can result in chemical changes that may turn the stool green. Thus, green stool by itself is only a sign of a change of the speed with which stool is traveling and not necessarily a sign of disease. On the other hand, if the entry of bile into the intestines is blocked, for example, by a tumor of the bile ducts or pancreatic cancer, the stool becomes clay-colored. Clay-colored stool always is a sign of important disease.
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