Jaundice

Jaundice is caused by a build-up of a substance called bilirubin in the blood and tissues of the body.

Bilirubin is a waste product that’s produced when red blood cells break down. Human blood cells have a lifespan of 120 days, after which they’re broken down and replaced with new cells.

The bilirubin is transported in the bloodstream to the liver where specialised cells help to combine it with digestive fluid called bile. Bile is stored in the gall bladder and is released into the digestive system through a series of tubes known as the bile duct system or biliary system.

The bile (and bilirubin contained with it) is converted by bacteria inside the digestive system into a substance called urobilinogen, which is passed out of the body in urine (in very small quantities) or in stools. It is bilirubin that gives urine its light yellow colour and stools their dark brown colour.

Jaundice can occur as a result of any condition, problem or underlying factor that disrupts the movement of bilirubin from the blood to the liver and then out of the body.

Pre-hepatic jaundice

Pre-hepatic jaundice occurs when a condition or infection speeds up the breakdown of red blood cells. This results in an increase in bilirubin levels in the blood and triggers the symptoms of jaundice.

Causes of pre-hepatic jaundice include:

• malaria – a blood-borne infection spread by mosquitoes and common in tropical areas of the world
• sickle cell anaemia – a genetic condition that causes red blood cells to develop abnormally; sickle cell anaemia is most common among black Caribbean, black African and black British people
• thalassaemia – a similar genetic condition to sickle cell anaemia in that it affects the production of red blood cells; thalassaemia is most common in people of Mediterranean, Middle Eastern and, in particular, South Asian, descent
• Gilbert’s syndrome – a common genetic condition where the transportation of bilirubin from the blood to the liver is slower than it should be, leading to a build-up of bilirubin in the blood
• Crigler-Najjar syndrome – a rare genetic condition where an enzyme that’s need to help move bilirubin out of the blood and into the liver is missing
• hereditary spherocytosis – an uncommon genetic condition that causes red blood cells to have a much shorter life-span than normal

Intra-hepatic jaundice

Intra-hepatic jaundice occurs when damage to the liver, either as the result of infection or exposure to a harmful substance, such as alcohol, disrupts the liver’s ability to process bilirubin.

Causes of intra-hepatic jaundice include:

• the viral hepatitis group of infections – hepatitis A, hepatitis B and hepatitis C
• alcoholic liver disease – where the liver is damaged as a result of alcohol misuse
• leptospirosis – a bacterial infection that’s spread by animals, particularly rats; it’s common in tropical areas of the world and uncommon in the UK
• glandular fever – a viral infection that’s caused by the Epstein-Barr virus
• drug misuse – two leading causes are the recreational drug, ecstasy, and overdoses of the painkiller, paracetamol
• primary biliary cirrhosis – a rare and poorly understood condition that causes progressive liver damage
• liver cancer – a rare and usually incurable cancer that develops inside the liver
• exposure to substances that are known to be harmful to the liver, such as phenol (a compound used in the manufacture of plastic) or carbon tetrachloride (a compound that was widely used in the past in processes such as refrigeration, although now its use is strictly controlled)
• autoimmune hepatitis – a rare condition where the immune system (the body’s natural defence against infection and illness) starts to attack the liver
• primary sclerosing cholangitis – a rare type of liver disease that causes chronic (long-lasting) inflammation of the liver
• Dubin-Johnson syndrome – a rare genetic condition where the liver is unable to combine bilirubin with bile and move it out of the liver

Post-hepatic jaundice

Post-hepatic jaundice is triggered when the bile duct system is damaged, inflamed or obstructed, which results in the gallbladder being unable to move bile into the digestive system

Causes of post-hepatic jaundice include:

• gallstones obstructing the bile duct system
• pancreatic cancer – an uncommon type of cancer that develops inside the pancreas (a gland that helps with the digestion of food)
• gallbladder cancer or bile duct cancer, which are both relatively rare types of cancer
• pancreatitis – inflammation of the pancreas, which can either be acute pancreatitis (the inflammation only lasts for a few days) or chronic pancreatitis (the inflammation lasts for many years)

Causes of jaundice in newborn babies:

There are three main reasons why jaundice is common in new born babies:

• newborn babies have a greater number of red blood cells than adults
• the red blood cells in babies have a shorter lifespan than those found in adults, so they need to be broken down and replaced at a faster rate
• the process to break down and excrete the bilirubin is slower than it is in adults

By the time a baby is two weeks old, they are producing less bilirubin and their liver is more effective at removing it from the body which means the jaundice usually corrects itself without causing harm.

Breastfeeding your baby makes it more likely they will develop jaundice; which tends to last longer than in bottle-fed babies.

The reasons for this are unclear. A number of theories have been suggested, such as:

• when you first start breastfeeding it can be hard to provide all the nutrients your baby requires so they are not getting nutrients and fluids necessary to help their body break down and excrete bilirubin; this tends to only be a short-term issue
• breastfeeding may somehow cause the bilirubin in the intestines (part of the digestive system) to be re-absorbed back into the blood, instead of being passed out
• it is also possible that breast milk contains an unidentified, but harmless, substance that causes jaundice in newborn babies

If you are breastfeeding your baby, continue to do so even if your baby has symptoms of jaundice as they will pass in time. Benefits of breastfeeding outweigh any potential risks associated with jaundice. You may wish to discuss this further with your licensed health practitioner or midwife.

Your baby is more likely to need treatment for high levels of bilirubin in their blood if:

• they were born before the 38th week of your pregnancy
• you have another child that needed treatment for jaundice
• you intend to only breastfeed your baby (not bottle-feed as well)
• they develop jaundice within 24 hours of being born

There is also some evidence that babies with a low birth weight (less than 2 and a half kilos or 5.5 pounds) are more likely to need treatment for jaundice.

In some cases, jaundice may have an alternative cause. Some of these are described below.

• An underactive thyroid gland (hypothyroidism).
• Blood group incompatibility, when the mother and baby have different blood types, and these are mixed during the pregnancy or the birth.
• Rhesus factor disease, a condition that can occur if the mother has rhesus-negative blood, and the baby has rhesus-positive blood.
• An inherited enzyme deficiency (enzymes are proteins that speed up and control chemical reactions in the body), such as a deficiency of glucose-6-phosphate-dehydrogenase (G-6-PD), an enzyme that helps red blood cells function.
• The baby experiences bleeding in and around the skull (cephalohaematoma) due to a difficult delivery – this condition is not usually serious.
• The mother of the baby has diabetes.
• The baby has a urinary tract infection (an infection, usually bacterial, that develops inside any part of the body used to pass urine, such as the bladder)
• Crigler-Najjar syndrome, an inherited condition that adversely affects the enzyme responsible for processing bilirubin, leading to an excess build up of bilirubin.
• An obstruction or defect in the biliary system. The biliary system is made up of the bile ducts and gall bladder, and it creates and transports bile (a fluid used to help digest fatty foods).