What Is Gilbert Syndrome? What Causes Gilbert Syndrome?

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Main Category: Liver Disease / Hepatitis
Also Included In: Blood / Hematology
Article Date: 09 Oct 2009 - 12:00 PDT

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Gilbert syndrome, also known as hepatic dysfunction, benign familial icterus, constitutional hepatic dysfunction, unconjugated benign bilirubinemia and familial nonhemolytic jaundice, is a genetic condition. It is a mild liver disorder in which bloodstream levels of bilirubin - a liver enzyme - are abnormal. When red blood cells break down bilirubin is produced. People with Gilbert syndrome have mildly elevated levels of bilirubin pigment which can sometimes give them jaundice of the eyes (yellowing), and sometimes the skin. The condition is harmless and patients do not usually need treatment.

The liver of people with Gilbert syndrome does not properly process bilirubin. They do not remove it properly and it builds up.

Because it is harmless, Gilbert syndrome is not usually seen as a disease. Most people don't know they have the syndrome until a blood test reveals higher than normal bilirubin levels.

In the United States approximately 3% to 7% of the population has Gilbert syndrome, according to the National Institutes of Health (NIH) - some gastroenterologists believe the prevalence may be as high as 10%. The National Health Service (NHS) estimates that about 5% of the UK population is affected. It is more common among males than females.

According to Medilexicon's medical dictionary, familial nonhemolytic jaundice, benign familial icterus, constitutional hepatic dysfunction, or Gilbert syndrome is "mild jaundice due to increased amounts of unconjugated bilirubin in the plasma without evidence of liver damage, biliary obstruction, or hemolysis; thought to be due to an inborn error of metabolism in which the excretion of bilirubin by the liver is defective, ascribed to decreased conjugation of bilirubin as a glucuronide or impaired uptake of hepatic bilirubin; autosomal dominant inheritance."

Gilbert's syndrome was first described by French gastroenterologist Augustin Nicolas Gilbert (1958-1927) and colleagues in 1901.

What are the symptoms of Gilbert syndrome?

Most people who are affected don't know it. Levels of bilirubin usually stay within normal levels, and occasionally rise slightly.

Jaundice - there may be a yellow tinge to the whites of the eyes and the skin when bilirubin levels go up too high. Symptoms may become more obvious as a result of:

• Illness
• Infection
• Dehydration
• Stress
• Menstruation
• Overdoing things (overexertion)

Although bilirubin levels hardly ever reach dangerous levels, the resulting jaundice can be disturbing. Jaundice symptoms usually appear in the eyes first, and then the skin if bilirubin levels rise further.

The following symptoms may also be possible, but less common:

• Loss of appetite
• Nausea
• Fatigue
• Weakness
• Abdominal pain

What are the causes of Gilbert syndrome?

Hyperbilirubinemia - elevated blood levels of bilirubin - occurs because the reduced activity of the enzyme glucuronyltransferase which conjugates bilirubin. Conjugation, which takes place in the liver, makes the bilirubin water-soluble so that it can be excreted in the bile into the duodenum and is eventually removed from the body.

When a red blood cell is about 120 days old it is broken down into bilirubin by hemoglobin. The liver then converts bilirubin into a water-soluble form.

Gilbert's syndrome is caused by a faulty gene - a mutation of the UDP-glucuronosyltransferase gene. People inherit the syndrome from a parent. The bilirubin does not conjugate (convert) at the normal rate and accumulates in the bloodstream. When levels reach a certain point the patient may have symptoms of jaundice.

How is Gilbert syndrome diagnosed?

If a person has Gilbert syndrome and it is diagnosed, the diagnosis usually occurs in his/her late teens or early twenties. As diagnosis is fairly straightforward, a genetic test is not generally necessary.

A sample of the patient's blood will be taken for a full blood count. The doctor may also test to determine how well the patient's liver is functioning. Bilirubin levels in the bloodstream will also be tested.

If test results show that water-insoluble bilirubin levels are high, but other tests are normal, the doctor will diagnose Gilbert's syndrome.

Underlying conditions - If the patient has signs of jaundice the doctor may order some other tests to determine whether there might be any underlying diseases or conditions, such as:

Acute inflammation of the liver - may impair the ability of the liver to conjugate and secrete bilirubin.

Inflammation of the bile duct - may prevent the secretion of bile and removal of bilirubin.

Obstruction of the bile duct - prevents the liver from disposing of bilirubin.

Hemolytic anemia - bilirubin production increases when lots of erythrocytes are broken down.

Cholestasis - the flow of bile from the liver is interrupted. The bile containing conjugated bilirubin remains in the liver instead of being excreted.

Crigler-Najjar syndrome - an inherited condition that impairs the specific enzyme responsible for processing bilirubin, resulting in an excess of bilirubin.

Dubin-Johnson syndrome - an inherited form of chronic jaundice that prevents conjugated bilirubin from being secreted out of the liver's cells.

Pseudojaundice - a harmless form of jaundice in which the yellowing of the skin results from an excess of beta-carotene, not from an excess of bilirubin; usually from eating lots of carrots, pumpkin, or melon.

Tests may include:


• An ultrasound scan of the liver
• The patient fasts for 24 hours to see if bilirubin levels rise
• Genetic testing

Treatment for Gilbert syndrome

As Gilbert syndrome is considered to be harmless - does not usually cause any health problems - the doctor will tell the patient that no treatment is required. Although the symptoms of jaundice may be unsettling, they are intermittent and nothing to worry about.

Long-term monitoring for people with Gilbert syndrome is not typically needed. If you do notice worsening jaundice symptoms you should talk to your doctor so that he/she may rule out any other condition that may have developed.

Patients who find the jaundice symptoms too unsettling may benefit from Phenobarbital, a medication which lowers bilirubin levels. Phenobarbital may cause sedation and light-headedness. It is important for the patient to realize that in this case the medication is not being taken for health reasons.

What are the possible complications of Gilbert syndrome?

Gilbert syndrome will not damage the liver. Apart from jaundice, there are no known complications.

Some medications - low levels of glucuronyltransferase, the enzyme which processes bilirubin, may result in more severe side effects with some drugs, especially irinotecan (Camptosar), which is used to treat colon cancer. Patients with Gilbert syndrome taking irinotecan can have severe diarrhea.

Written by Christian Nordqvist


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