Gilbert's syndrome: symptoms, causes, diagnosis and what it means for you

Gilbert's syndrome is a common, long-term condition that can run in families. Liver UK describes it as a build-up of bilirubin in the blood that is usually considered harmless. It is often diagnosed by accident after a routine blood test for another reason, and most people are diagnosed in their teens or early 20s.

Bilirubin is a yellow chemical made when the liver breaks down old red blood cells. Normally it is removed from the body in poo, with the help of special proteins called enzymes. In Gilbert's syndrome there is a difference in one or more of these enzymes, so less bilirubin leaves in the poo and more stays in the blood.

The most common symptom, according to the NHS, is mild episodes of jaundice that come and go. The yellowing may be less noticeable on brown or black skin, but it may be easier to see in the white part of the eyes. Liver UK adds that many people have few or no symptoms and may not even know that they have the condition.

The NHS notes that jaundice can also cause itchy skin, darker pee and paler poo than usual, but Gilbert's syndrome does not usually cause these symptoms. If you have them, the jaundice is likely to be caused by something else and needs to be checked.

Jaundice can be a sign of something serious, such as liver disease, so the NHS says to get urgent medical help if your skin or the white part of your eyes look yellow and you have not been diagnosed with Gilbert's syndrome. Ask for an urgent GP appointment or get help from NHS 111.

If you have been diagnosed with Gilbert's syndrome, the NHS gives the same advice if the jaundice is worse than usual or does not go away within a few days.

The NHS jaundice page also notes that the cause can be one of several things, including alcohol-related liver disease, gallstones, hepatitis, pancreatitis or sickle cell disease.

The NHS says Gilbert's syndrome is caused by an altered gene passed on to a child by their parents. It is more common in men and in people with type 1 diabetes.

Liver UK explains that several variants are known to cause it and that in the UK the most common are in a gene called UGT1A1, which means you make less of an enzyme of the same name. The variant genes can be passed from parent to child, which is why it often runs in families, but the variants on their own do not always cause symptoms. Even if someone has the condition, other members of the family might not.

The NHS says you can try to prevent jaundice by keeping a record of it and avoiding things that trigger it, such as over-exercising, not getting enough sleep, drinking alcohol or not drinking enough fluids.

• Over-exercising.

• Not getting enough sleep.

• Drinking alcohol.

• Not drinking enough fluids.

The NHS says Gilbert's syndrome can be diagnosed with blood tests, including a test to check how well your liver is working, and that a genetic test is sometimes needed to confirm the diagnosis. Because it may not cause any symptoms, some people only find out they have it during tests for something else.

Liver UK says that if someone with Gilbert's syndrome has more serious symptoms it is important to have more tests, because it is possible to have another condition at the same time.

The NHS says there is currently no cure for Gilbert's syndrome, but it does not cause any damage to your liver and does not usually cause any serious health problems. It does not affect how long you will live. You may have a slightly increased risk of gallstones, but it does not increase your risk of any other conditions.

Liver UK agrees that it is usually considered harmless and that it does not cause cirrhosis or serious liver damage. It also says that most people will not need treatment, that it might increase the risk of getting gallstones and that it can affect how some medicines work.

The NHS advises speaking to a GP or pharmacist before taking any new medicines, because you may need to be more closely monitored while taking certain medicines, such as statins for high cholesterol.

Always tell prescribers that you have Gilbert's syndrome, and do not stop a prescribed medicine without advice.

Because both the NHS and Liver UK mention a possible slightly raised risk of gallstones, it helps to know the signs. The NHS says gallstones are common and often cause no symptoms, but if a gallstone blocks a bile duct it can cause severe, constant tummy pain, lasting longer than 30 minutes and up to several hours, in the middle of the tummy or just under the ribs on the right side, sometimes with feeling or being sick.

The NHS says to ask for an urgent GP appointment or call 111 for tummy pain lasting longer than 30 minutes, and to call 999 or go to A&E for sudden severe tummy pain, pain spreading to the back with being sick, a very high temperature or feeling hot, cold or shivery, or yellowing of the skin or eyes.

Gilbert's syndrome is usually picked up through a GP blood test and needs no specialist treatment. A GP can arrange liver blood tests and, if the picture is unclear, refer you to a liver specialist (hepatologist) or gastroenterologist.

Some people choose private liver blood tests or a private specialist opinion. Whichever route, new jaundice that has not been explained should be looked at urgently, and not assumed to be Gilbert's syndrome.