Seeing white or pale-colored stool can be alarming, as it deviates from the expected brown hue. Stool color directly indicates the health and function of the digestive system, especially the organs regulating digestive fluids. A sudden or persistent change to a pale, white, or clay-like color, medically termed acholic stool, often signals a reduction or absence of bile pigments reaching the intestinal tract. This color change can result from temporary side effects or more serious internal conditions.
The Biology of Poop Color
The typical brown color of human stool comes from stercobilin, a breakdown product of blood cells. When red blood cells break down, they release heme, which the liver processes into a yellowish pigment called bilirubin. Bilirubin is a component of bile, a fluid produced by the liver and stored in the gallbladder, which aids in fat digestion.
Bile is released into the small intestine, where gut bacteria convert the bilirubin into stercobilin, which is dark brown. The presence of stercobilin gives feces their characteristic shade. If the stool appears pale, the normal flow of bilirubin-containing bile has been interrupted, preventing the formation of this pigment.
Dietary and Medication-Related Causes
Not all instances of pale stool indicate internal organ dysfunction; some are temporary side effects of ingestion. Certain medications can alter stool color by binding to substances in the digestive tract.
Medications
Antacids containing aluminum hydroxide can cause pale or white speckles in the stool. Aluminum hydroxide neutralizes stomach acid and binds to phosphates, forming insoluble white aluminum salts that are excreted. Large doses of Bismuth subsalicylate compounds, used for upset stomachs and diarrhea, can also cause a pale appearance, although Bismuth typically results in a black or grayish stool.
Medical Procedures
A temporary, bright white stool may follow an imaging procedure using barium. Barium sulfate is a chalky white contrast agent used to coat the digestive tract for X-rays. Since the body does not absorb barium, it passes through and leaves the stool visibly white for a couple of days until it is fully cleared.
Underlying Medical Conditions
Persistent paleness not linked to diet or medication often indicates a problem with bile flow, known as biliary obstruction. This results in acholic or clay-colored stool because the necessary bilirubin pigment is absent from the waste. The most common cause of this blockage is gallstones, which are hard deposits formed in the gallbladder.
A gallstone can become lodged in the common bile duct, which carries bile from the liver and gallbladder to the small intestine. When this duct is blocked, bile cannot enter the digestive system to mix with the stool, resulting in the pale color. Obstruction can also be caused by severe inflammation of the pancreas (pancreatitis), which may swell and compress the common bile duct.
Liver diseases, such as hepatitis or cirrhosis, can also cause pale stool by impairing the liver’s ability to produce bile or process bilirubin effectively. If the body cannot produce or excrete bile, the stool lacks the necessary brown pigment. Another cause is steatorrhea, or fatty stool, which is bulky, foul-smelling, and appears pale or greasy due to undigested fat content.
When to Seek Professional Medical Guidance
A single instance of pale stool may not warrant concern, especially if linked to a known medication or recent procedure. However, if the white or clay-colored stool continues for more than a day or two, consultation with a healthcare provider is recommended.
Immediate attention is necessary if pale stool is accompanied by symptoms indicating a significant blockage in the biliary system. These accompanying signs suggest a need for urgent professional evaluation:
- Jaundice (yellowing of the skin and whites of the eyes) caused by bilirubin buildup.
- Darkening of the urine, as the body attempts to excrete backed-up bilirubin.
- Severe abdominal pain.
- Nausea or vomiting.
- Unexplained weight loss.