Bilirubin is a yellow pigment produced from hemoglobin in red blood cells. At end of their life span, red blood cells travel to the spleen, where they are broken down and their hemoglobin is converted into bilirubin by a series of biochemical reactions. The bilirubin is transported to the liver, where it is conjugated (attached) to another molecule, making it water soluble. It then moves on to the gall bladder as a component of bile. Bile is released into the intestines through the common bile duct during digestion. Eventually, the bilirubin is excreted from the body through the feces or else reabsorbed by the intestines, transported to the kidneys and excreted through the urine.
There are three categories of jaundice, depending on which part of the bilirubin metabolic pathway is affected.
Pre-hepatic jaundice, also known as unconjugated or hemolytic jaundice, is caused by a disorder that occurs before the bilirubin reaches the liver. Hemolytic disorders increase the rate of red blood cell destruction so that bilirubin is produced faster than it can be processed by the liver and excreted. Some examples of hemolytic diseases are malaria, sickle cell anemia, and other hereditary red blood cell and small blood vessel disorders. Other causes of pre-hepatic jaundice include immune reactions, kidney failure, and enlargement of the spleen.
Hepatic or hepatocellular jaundice occurs if the condition is within the liver. Some causes are inflammation of the liver due to viral hepatitis B and C, alcoholic liver disease with cirrhosis, genetic diseases, drug reactions and liver cancer.
Post-hepatic jaundice, also called obstructive or cholestatic jaundice, results when there is a blockage in the bile ducts preventing the bilirubin to travel from the gallbladder to the intestines. This type of jaundice is often caused by gallstones in the biliary ducts. It can also result from pancreatic cancer.
Neonatal jaundice is common in newborn infants, particularly if they are premature, because the liver is not yet fully functional. Phototherapy, exposing the infant to bright light for short periods of time each day, helps to change the bilirubin into a harmless form. It is important to carefully monitor the bilirubin levels in newborns, because the bilirubin can cause brain damage if the levels are too high for an extended period of time.
The treatment of jaundice depends on its underlying cause. Laboratory tests can help to determine where in the metabolic pathway the problem is located, and the treatment would address the specific disease, such as malaria or viral hepatitis. Treatment of obstructive jaundice may require surgical removal of gallstones, or even the gallbladder or pancreas. If the liver is damaged by alcoholism or abuse of drugs, it may begin to heal and regenerate once the harmful substance is no longer present.
References:
http://www.ahealthyme.com/article/gale/100083576
http://www.britannica.com/EBchecked/topic/301639/jaundice
Published by Terrie Schultz
Terrie Schultz worked for many years in the biomedical field doing research and development in the areas of cancer, HIV and hepatitis. She has also taught middle school physical science, earth science, read... View profile
- Sickle Cell Disease - Sickle Shaped Cells in the BloodSickle Cell Disease is a disorder in the blood where some of the red blood cells are misshapen and do not function as normal red blood cells do. It is estimated that about 1/400 African Americans are carriers of the S...
- High Blood Pressure and Some CausesWe've all heard that salt raises blood pressure but what about other everyday things that we might not have heard about?
- Donating Blood, Double Red Cells, Plasma, and PlateletsThere are more ways to save lives with your own blood. I have covered some of the methods used and what types of blood donations there are.
- Complete Blood CountThe complete blood count (CBC) measures several values that can help your doctor diagnose medical conditions or determine the need for additional tests. Learn what this test measures and why it's ordered.
Canine and Feline Blood DonationsInformation about canine and feline blood donation.
- Double Red Blood Cell Donations
- A Guide to the Functions of Red Blood Cells
- What is Blood Doping?
- Incurable Polycythemia Vera Causes Death from Blood Clots
- Liver Disease Causes, Symptoms, and Treatment. A General Guide to Liver Diseases
- Riboflavin: Build Red Blood Cells and Halt Production of Cancer Cells
- All About White Blood Cells
- Jaundice may be a sign of a serious disease.
- If you have symptoms of jaundice, see your health care provider to find out what is causing it.
