[0:04]Gallstones are hard deposits or simply stones that form inside the gallbladder. This condition is also known by the Greek name cholelithiasis. Chola means bile, lith comes from the word lithos meaning stone, and iasis refers to an abnormal condition in the body. Put it all together, and cholelithiasis means having bile stones. Now, picture yourself enjoying a creamy plate of Greek moussaka. As those fats move through your digestive system, they finally reach the small intestine. But fats are difficult to process, and that's where the small pear-shaped organ gallbladder steps in. Enjoying our Osmosis videos? Unlock your full potential with an Osmosis subscription. Get unlimited access to every Osmosis feature and resource with a free 7-day trial. The gallbladder acts as a storage tank for bile produced by the liver. The liver carefully blends this digestive smoothie with just the right mix of bile salts, phospholipids, cholesterol, and bilirubin. The liver starts the recipe by converting cholesterol into bile acids, such as cholic acid. Then it mixes these bile acids with amino acids like taurine to create water-soluble bile salts that flow smoothly into the bile. But not all cholesterol takes this path. Some slip directly into bile as free cholesterol, where it mixes with bile salts and phospholipids like lecithin. These ingredients act like tiny detergents, wrapping around cholesterol molecules to keep them from crystallizing and clumping. Another key ingredient in bile is bilirubin, which comes from the natural breakdown of red blood cells. When red blood cells reach the end of their life, they release hemoglobin, which is further broken down into heme and globin. The body converts heme into biliverdin and biliverdin to unconjugated bilirubin. However, unconjugated bilirubin isn't water soluble, so it binds to albumin to hitch a ride to the liver. In the liver, the body transforms unconjugated bilirubin into water-soluble conjugated bilirubin, ready for excretion into bile.
[2:29]The liver produces bile continuously, sending it either directly to the small intestine or to the gallbladder for storage. The gallbladder walls, which are lined and coated with protective mucus, absorb water and electrolytes, concentrating the bile up to 10 times its original strength. Most of the time, the liver blends this bile smoothie perfectly, but sometimes, things go off the recipe. The bile becomes too thick or the gallbladder doesn't empty as it should. That's when gallstones form, and depending on their main ingredient, they can be cholesterol stones and pigmented stones. Cholesterol stones are the most common ones, and they develop exclusively in the gallbladder for several reasons. The main one is supersaturation with cholesterol, which happens when the bile recipe is off. Basically, the liver adds too much free cholesterol, but not enough bile salts and phospholipids. It's like pouring too much protein powder into your smoothie. Instead of blending smoothly, it starts to clump together.
[3:40]The second reason is gallbladder stasis, also known as gallbladder hypomotility, which means the gallbladder isn't contracting the way it should. Just like a smoothie that sits out too long and starts to separate, a stagnant bile gives cholesterol molecules time to clump together. Finally, the gallbladder can produce more mucus than it should. This thick layer creates the perfect environment to trap cholesterol crystals, allowing them to clump together. It's like adding too much syrup to your smoothie. As cholesterol crystals clump together within the gallbladder, they slowly grow into oval and firm cholesterol stones. Sometimes there's just one, but more often, there are several stones lying side by side. As they grow, they press against each other and develop flat, smooth surfaces where they touch. When made of pure cholesterol, cholesterol stones have a pale yellow color. However, they can also pick up substances, such as calcium carbonate, phosphates, and bilirubin, so their color can range from gray to white or even black. On the other hand, pigment stones make up a smaller portion of gallstones and can appear anywhere along the biliary tree. These stones come in two colors and form when bile contains too much unconjugated bilirubin.
[5:06]Black pigment stones usually form in the sterile bile of the gallbladder and develop in people with chronic hemolytic anemias. In these individuals, high levels of unconjugated bilirubin overwhelms the liver's ability to process it. As a result, unconjugated bilirubin, along with conjugated, appears in bile. Unconjugated bilirubin binds with calcium to form black stones made of calcium bilirubinate, which are usually small, numerous, and fragile to the touch. Next, brown stones usually form in people with biliary tract infections, such as liver flukes. These pathogens often release an enzyme called beta-glucuronidase, which converts conjugated bilirubin back into its unconjugated form. This unconjugated bilirubin then binds with calcium, leading to the formation of brown stones made of calcium bilirubinate. Sometimes, they can also include other calcium salts and cholesterol.
[6:06]Compared to black stones, brown stones are usually fewer in number and softer, with a greasy, soap-like texture. This soapy feel comes from another enzyme released by pathogens. It's called phospholipase, which breaks down phospholipids and enables the formation of calcium salts of fatty acids. Several factors can tip the balance toward stone formation, and you can use the pneumonic MAGICS to remember them. M stands for metabolic factors like obesity. A stands for age, as risk increases with age, and G represents gallbladder stasis, like an individual's on total parenteral nutrition. Next, I stands for inherited, because family history is a risk factor. C stands for childbearing and oral contraceptives, both of which are associated with elevated estrogen levels. Finally, S refers to sex, because biologically female individuals have a higher risk, again, thanks to estrogen activity. Most of the time, gallstones stay silent. But for some, that calm can be shattered by biliary colic, unleashing sharp, intense pain in the upper right abdomen or just below the ribs. Biliary colic typically follows a fatty meal, as fat triggers the gallbladder to contract, pushing a stone against its outlet and causing pressure to build. As pressure rises, the gallbladder walls stretch, making the pain peak within 15 to 60 minutes. The pain holds steady for 1 to 4 hours before gradually easing as the stone shifts back or passes through the duct. Often, symptoms like nausea, vomiting, and sweating accompany biliary colic, while people typically feel normal between episodes. Diagnosis primarily relies on abdominal ultrasound, which identifies gallstones in over 90% of cases. Ultrasound may also show bile duct dilation if a stone has recently passed or is still present. Abdominal X-ray can be done if the cause of the pain is uncertain, but most cholesterol stones are radiolucent and don't show up. However, if they contain calcium salts, such as calcium carbonate, they become radiopaque and visible. Similarly, black pigment stones contain high concentrations of calcium bilirubinate, which makes them radiopaque, while brown pigment stones contain calcium salts of fatty acids, which makes them radiolucent. If needed, you can turn to more advanced tools like magnetic resonance cholangiopancreatography, which maps the bile ducts and identifies stones as filling defects. Also, during the endoscopic retrograde cholangiopancreatography, you can inject dye into the bile ducts and take X-rays to locate stones. If present, you can remove them during the same procedure.
[9:02]Most gallstones don't cause symptoms, so surgery is usually not worth the risks unless they start causing problems. When symptoms do occur, the go-to treatment is laparoscopic cholecystectomy, which is the surgical removal of the gallbladder through small cuts with the help of a tiny camera. For individuals who can't have surgery, alternatives include medications that help dissolve the stones, like ursodeoxycholic acid. All right, as a quick recap. Gallstones or cholelithiasis, form when substances in bile, primarily cholesterol or unconjugated bilirubin, crystallize within the gallbladder. Cholesterol stones develop if there's too much cholesterol or insufficient bile salts, while pigment stones arise when excess unconjugated bilirubin binds calcium, often due to increased red blood cell breakdown or infections.
[10:07]Helping current and future clinicians focus, learn, retain, and thrive. Learn more at osmosis.org.
