Jaundice is caused by a buildup of bilirubin, a yellow pigment produced when your body breaks down old red blood cells. In healthy adults, total bilirubin levels stay between 0.3 and 1.0 mg/dL. When bilirubin rises above about 2.5 to 3.0 mg/dL, it starts to visibly stain your skin, the whites of your eyes, and the tissue inside your mouth a yellowish color. The buildup happens for one of three broad reasons: your body is producing too much bilirubin, your liver can’t process it fast enough, or something is blocking it from leaving your body.
How Your Body Normally Handles Bilirubin
Understanding why bilirubin builds up starts with knowing how it normally moves through your body. Red blood cells live about 120 days. When they wear out, cells in your spleen and other parts of your immune system break them down. The hemoglobin inside those cells gets converted first into a green pigment called biliverdin, then into bilirubin, which is yellow and doesn’t dissolve in water.
Because bilirubin can’t dissolve in blood on its own, it hitches a ride on a protein called albumin, which carries it to the liver. Inside liver cells, an enzyme attaches bilirubin to a sugar molecule, making it water-soluble. This processed (conjugated) bilirubin then gets pumped into bile, flows through the bile ducts into your intestine, and eventually leaves your body in stool. Bacteria in your gut convert some of it into the brown pigment that gives stool its normal color. A small amount is reabsorbed and filtered out through your kidneys, giving urine its yellow tint.
A problem at any step in this chain, from red blood cell breakdown to bile flow into the intestine, can cause bilirubin to accumulate and produce jaundice.
Too Much Bilirubin Being Produced
When red blood cells are destroyed faster than normal, the liver simply can’t keep up with the flood of bilirubin. This is called pre-hepatic jaundice because the problem starts before bilirubin even reaches the liver. The bilirubin that builds up in these cases is the unconjugated (unprocessed) form.
Several conditions cause this kind of rapid red blood cell destruction:
- Sickle cell anemia: Abnormally shaped red blood cells get trapped and destroyed in small blood vessels, the spleen, or the liver.
- Thalassemia: A group of inherited blood disorders that produce fragile red blood cells easily destroyed by the body.
- G6PD deficiency: A genetic condition affecting an enzyme that protects red blood cells. Without enough of it, certain infections or medications can trigger red blood cells to break apart.
- Autoimmune hemolytic anemia: The immune system mistakenly identifies red blood cells as threats and produces antibodies that destroy them.
- Mismatched blood transfusions: Receiving blood from an incompatible donor triggers rapid destruction of the transfused cells.
Liver Damage or Disease
When the liver itself is diseased or inflamed, its cells lose the ability to process bilirubin efficiently. This is hepatic (or hepatocellular) jaundice. Both conjugated and unconjugated bilirubin levels tend to rise, because damaged liver cells can’t take in bilirubin properly and may also leak already-processed bilirubin back into the bloodstream.
The most common culprits are viral hepatitis (especially hepatitis B and C) and chronic alcohol use, both of which can progressively scar the liver into a condition called cirrhosis. In cirrhosis, so much healthy tissue has been replaced by scar tissue that the liver can no longer perform its normal functions, including bilirubin processing.
Less common liver conditions that cause jaundice include autoimmune hepatitis, where the immune system attacks liver cells directly; hemochromatosis, a disorder of iron buildup in the body; Wilson’s disease, which causes copper to accumulate in the liver; and primary sclerosing cholangitis, where the bile ducts inside the liver become inflamed and scarred. Certain medications and toxins can also damage liver cells enough to trigger jaundice.
Blocked Bile Ducts
Even when the liver processes bilirubin correctly, a physical blockage in the bile ducts can trap it. This is post-hepatic or obstructive jaundice, and it causes conjugated bilirubin to back up into the bloodstream because it has nowhere else to go.
Gallstones are the most common benign cause. A stone formed in the gallbladder can migrate into the common bile duct and block bile flow entirely. Inflammation from conditions like pancreatitis can also compress the ducts from the outside. Strictures (abnormal narrowing of the ducts from scarring or prior surgery) and infections are other non-cancerous causes.
On the more serious end, several cancers can obstruct bile ducts. Pancreatic cancer is a frequent cause because the head of the pancreas sits right next to the common bile duct. Cancer of the bile ducts themselves (cholangiocarcinoma), gallbladder cancer, and tumors that have spread to the liver from elsewhere in the body can all produce obstructive jaundice.
Symptoms That Accompany Obstructive Jaundice
Obstructive jaundice often produces a distinctive pattern beyond yellow skin. When bile can’t reach the intestine, stool loses the pigment that normally makes it brown. The result is pale or clay-colored stool. At the same time, the excess conjugated bilirubin trapped in the blood gets filtered out through the kidneys, turning urine noticeably dark. Intense itching is also common, caused by bile salts depositing in the skin. If you notice this combination of pale stool, dark urine, and yellowing skin, it typically points to a blockage rather than a liver or blood cell problem.
Gilbert Syndrome
Not all jaundice signals a serious problem. Gilbert syndrome is a common, harmless genetic condition where the liver produces less of the enzyme needed to process bilirubin. It affects roughly 3 to 7 percent of the population, and most people with it never know they have it unless a blood test reveals mildly elevated bilirubin.
The condition requires inheriting two copies of a modified gene, one from each parent. In everyday life, bilirubin levels stay near normal. But certain triggers can push them high enough to cause visible yellowing, particularly in the eyes. These triggers include fasting or eating very few calories, dehydration, illness like a cold or flu, strenuous exercise, stress, and menstruation. The yellowing resolves on its own once the trigger passes, and the condition doesn’t damage the liver.
Jaundice in Newborns
Newborn jaundice is extremely common, appearing in the majority of babies within the first few days of life. It happens for two reasons occurring at the same time. First, newborns break down red blood cells faster than adults because fetal red blood cells have a shorter lifespan and babies are born with a higher volume of them. Second, a newborn’s liver is immature. It has low levels of the enzyme that conjugates bilirubin and low amounts of the binding proteins that move bilirubin through liver cells.
This combination, high production plus slow processing, is called physiologic jaundice. It typically peaks around day 3 to 5 and resolves on its own within one to two weeks as the liver matures. Bilirubin levels that doctors consider significant level off at around 17 mg/dL in full-term infants and 14 mg/dL in preterm babies.
Some newborns are at higher risk for more severe jaundice. Babies with G6PD deficiency, hereditary spherocytosis, or blood type incompatibility with their mother (ABO hemolytic disease) break down red blood cells even faster. Infants who also carry the Gilbert syndrome gene face a compounded risk. One genetic study found that a combination of two specific gene variants increased the risk of marked newborn jaundice by 22-fold. When bilirubin rises too high, phototherapy (treatment with special blue-spectrum lights) is used to convert bilirubin in the skin into a form the baby can excrete without liver processing.
How Jaundice Is Diagnosed
A bilirubin blood test is the starting point. It measures total bilirubin and breaks it into direct (conjugated) and indirect (unconjugated) fractions. The ratio between these two numbers helps narrow down the cause. High unconjugated bilirubin points toward excess red blood cell breakdown or a processing problem like Gilbert syndrome. High conjugated bilirubin suggests a liver disease or bile duct obstruction.
From there, further testing depends on what the initial results suggest. Liver function tests measure enzymes and proteins that indicate how well the liver is working. Urine tests can detect bilirubin that has spilled into the urine, which only happens with conjugated bilirubin. An ultrasound is commonly used to look for gallstones, bile duct dilation, or masses in the liver or pancreas. In some cases, a liver biopsy may be needed to examine tissue under a microscope and identify the specific type of liver disease causing the problem.