What causes jaundice

What is Jaundice?

Jaundice, medically known as hyperbilirubinemia, is a common condition characterized by a yellowish discoloration of the skin, sclera (the white part of the eyes), and mucous membranes. This yellowing is a visible sign that there is an excess of bilirubin in the bloodstream. Bilirubin is a yellowish-orange pigment that is produced during the normal process of red blood cell breakdown. When red blood cells reach the end of their lifespan (about 120 days), they are broken down in the spleen, liver, and bone marrow, and bilirubin is a byproduct of this process.

How Bilirubin is Processed

Normally, bilirubin travels through the bloodstream to the liver. In the liver, it is processed (conjugated) by enzymes, making it water-soluble. This conjugated bilirubin is then excreted into the bile, a fluid produced by the liver that aids in digestion. Bile is stored in the gallbladder and released into the small intestine to help break down fats. From the small intestine, bilirubin is further processed by bacteria and eventually eliminated from the body in stool (giving it its brown color) and, to a lesser extent, in urine.

Causes of Jaundice

Jaundice arises when this delicate bilirubin processing system is disrupted at any stage. The causes can be broadly categorized into three main types:

1. Pre-hepatic Jaundice (Before the Liver)

This occurs when there is an excessive rate of red blood cell breakdown (hemolysis), leading to more bilirubin being produced than the liver can process. Conditions that can cause pre-hepatic jaundice include:

• Hemolytic anemias: These are disorders where red blood cells are destroyed prematurely. Examples include sickle cell anemia, thalassemia, autoimmune hemolytic anemia, and malaria.
• Ineffective erythropoiesis: Conditions where red blood cells are produced abnormally and destroyed before they can mature, such as in certain types of megaloblastic anemia.
• Reactions to certain medications or blood transfusions.

In these cases, the liver itself is functioning normally, but it's overwhelmed by the sheer volume of bilirubin being produced.

2. Hepatic Jaundice (Within the Liver)

This type of jaundice occurs when the liver itself is damaged or diseased, impairing its ability to take up, process, or excrete bilirubin. Common causes of hepatic jaundice include:

• Hepatitis: Inflammation of the liver, often caused by viral infections (Hepatitis A, B, C, D, E), alcohol abuse, autoimmune diseases, or certain medications.
• Cirrhosis: Scarring of the liver tissue, which can result from chronic hepatitis, long-term alcohol abuse, or other liver damage. This scarring disrupts normal liver function.
• Gilbert's syndrome: A common, harmless genetic disorder where the liver has a reduced ability to process bilirubin. It typically causes mild jaundice that appears during periods of stress, illness, or fasting.
• Crigler-Najjar syndrome: A rare genetic disorder affecting the enzyme needed to process bilirubin.
• Certain medications: Some drugs can directly damage the liver or interfere with its bilirubin processing capabilities.
• Liver cancer or metastatic cancer (cancer that has spread to the liver from elsewhere).

In hepatic jaundice, the liver's capacity to conjugate and excrete bilirubin is compromised.

3. Post-hepatic Jaundice (After the Liver - Bile Duct Obstruction)

This occurs when there is a blockage in the bile ducts, preventing the processed bilirubin (in bile) from being excreted into the intestine. This causes bilirubin to back up into the bloodstream. Causes of post-hepatic jaundice include:

• Gallstones: Stones in the gallbladder can migrate and block the common bile duct.
• Tumors: Cancers of the pancreas, bile ducts, or gallbladder can press on or obstruct the bile ducts.
• Inflammation or scarring of the bile ducts (e.g., from infection or surgery).
• Pancreatitis: Inflammation of the pancreas, which can sometimes compress the bile duct.

In post-hepatic jaundice, the liver is producing conjugated bilirubin correctly, but its exit route is blocked.

Jaundice in Newborns

Jaundice is very common in newborns, often referred to as neonatal jaundice. This is usually physiological jaundice, meaning it's a normal, temporary condition. Newborns have a higher rate of red blood cell breakdown, and their immature livers take a few days to learn how to process bilirubin efficiently. Most cases of newborn jaundice are mild and resolve on their own within a week or two. However, in some cases, it can become severe (pathological jaundice) and require treatment, such as phototherapy (light therapy), to prevent brain damage (kernicterus).

When to Seek Medical Advice

While mild jaundice in newborns often resolves naturally, jaundice in adults or persistent jaundice in infants always warrants medical evaluation. It is crucial to determine the underlying cause, as it can range from a benign condition like Gilbert's syndrome to serious diseases like hepatitis, cirrhosis, or cancer. A healthcare provider will perform a physical examination, take a medical history, and likely order blood tests to measure bilirubin levels and assess liver function. Imaging tests like an ultrasound or CT scan may also be used to examine the liver and bile ducts.