Final answer:
White chalky stool is often the result of a lack of bile entering the intestines, usually due to an obstruction like gallstones in the bile duct. This leads to 'acholic' stools and can also cause jaundice due to the accumulation of bilirubin.
Step-by-step explanation:
White chalky stool is commonly caused by a lack of bile reaching the intestines. This condition can occur due to an obstruction such as gallstones blocking the bile duct, preventing bile from being excreted. Bile, a yellowish green liquid essential for digestion, is produced in the liver and contains bile salts, bile pigments, and other compounds. Bile salts are crucial for the emulsification and absorption of lipids.
When bile doesn't enter the intestine, stools lack the brown pigment called stercobilin, which is typically formed from bilirubin by intestinal bacteria. This results in pale or white, 'acholic' stools. Furthermore, without bile, fats are poorly absorbed, leading to a higher fat content in the stool—a condition known as steatorrhoea.
It is important to note that gallstones are solid particles formed from cholesterol and other substances within the gallbladder. When large gallstones obstruct the bile duct, they can also cause jaundice, visualized by a yellowing of the skin and eye whites due to the buildup of bilirubin—a breakdown product of red blood cells processed by the liver.