The term “jaundice” is used to describe patients who have gone yellow due to the accumulation of bile pigments in the bloodstream. It is also termed “icterus”.
In the normal person, old blood cells are broken down when they reach the end of their useful life, and the red pigment called haemoglobin is taken by the liver, and converted into bile pigments. Pigments are called billirubin (a redish pigment) and biliverdin (a green pigment).
These bile pigments are then passed from the liver as waste products, into the upper bowel called the small intetestine (actually the duodenum). The bile pigments pass from the liver down the common bile duct, which then passes through the pancreas in into the duodenum. The gallbladder is a “sac” that comes off the side of the common bile duct and is used as a storage of bile. During a meal, the gallbladder contracts and the bile which includes the bile pigments, squirted down the common bile duct into the duodenum.
The bile pigments mix with the contents of the bowel and it is due to the bile pigments that the faeces are brown.
Jaundice occurs for one of three reasons:
The first, and least common, is called pre-hepatic jaundice.
In pre-hepatic jaundice, there is an excessive breakdown of blood and therefore haemoglobin, resulting in haemoglobin being broken down as it passes through the liver as part of the normal liver blood supply. The bile pigments stay in the blood and are not passed into the bile. This can be tested for in laboratories and is called “unconjugated”.
The second, and most common, is called hepatic jaundice.
In hepatic jaundice, it is a disease of the liver in itself that is preventing the normal passage of the bile pigments into the bile ducts. As such they spill back into the blood causing jaundice. Diseases that cause hepatic jaundice include cirrhosis, hepatitis, reactions to drugs, cancer and infections called hepatitis. There are many forms of hepatitis, the commonest being a viral hepatitis which has many different subtypes.
The third cause is posthepatic jaundice. Post-hepatic jaundice is also called cholestatic jaundice (meaning that the bile has stopped moving) and surgeons often called this obstructive jaundice. However not all causes of posthepatic jaundice are obstructive. Cholestatic jaundice is diagnosed if the bile ducts are all clear and the bile could go into the duodenum, but it does not. One of the commonest causes of this is drugs such as the phenothiazines (such as chlorpromazine and the major tranquillisers).
Obstructive jaundice occurs when there is an obstruction stopping the flow of bile down its normal route. The more common causes of this include gallstones and cancer of the pancreas.
The effects of jaundice:
Jaundice is seen by a yellowing of all of the body, due to the high levels of circulating bile pigments in the blood supply. Not only is the skin yellow, but if you check the use, and even the whites of the eyes (the sclera) have turned yellow.
The bile pigments passed out of the blood in the kidneys, making the urine much darker. At the same time, as the bile pigments are not getting into the bowel, the faeces are not stained brown and so become much lighter in colour – often pale yellow or cream.
Jaundice is usually associated with itching (called pruritus). This is not an effect of the bile pigments, but is an effect of the other waste products such as the bile salts that similarly are not being passed down the common bile duct and out of the body through the bowel.
Tests for jaundice:
If jaundice is suspected, not only is the skin starting to look yellow but the whites of the eyes are also becoming yellow. The urine starts becoming darker and usually the stools lighter. A simple urine test will show if bilirubin is present in the urine. A blood test can measure the level of bilirubin circulating in the blood stream.
Once this diagnosis has been made, it is essential to find the underlying cause for the jaundice. As can be seen from above, there so many causes that the specific tests required to depend totally on what the likely underlying cause is.
Therefore it is essential that anyone who develops jaundice is seen by a specialist as soon as possible to determine whether the jaundice is a marker of a more serious underlying condition.