Patient information: Gilbert's syndrome

GILBERT'S SYNDROME OVERVIEW

Gilbert's syndrome, also known as constitutional hepatic dysfunction or familial nonhemolytic jaundice, is an inherited disorder of the liver that results in an overabundance of a substance known as bilirubin. While some people with Gilbert's syndrome develop yellowing of the skin or eyes, most people have no symptoms at all. It is not necessary to treat Gilbert's syndrome.

WHAT IS BILIRUBIN?

Bilirubin is normally present in the blood in small amounts. It is a by-product of the breakdown of hemoglobin in old red blood cells, and it is usually converted by the liver into a form that can be excreted from the body in stool. Abnormalities in this process can cause blood levels of bilirubin to rise above normal.

People with Gilbert's syndrome have an inherited abnormality that causes reduced production of an enzyme involved in processing bilirubin. (See "Gilbert's syndrome and unconjugated hyperbilirubinemia due to bilirubin overproduction".)

Every affected person has two copies of the abnormal gene responsible for Gilbert's syndrome. Because over half of the people in the general population have at least one abnormal copy of the gene, inheriting two abnormal copies (one from the mother and one from the father) is not uncommon. Interestingly, people who have only one copy may have slightly higher levels of unconjugated bilirubin but do not have Gilbert's syndrome. For reasons that are not entirely understood, not all people who have two copies of the abnormal gene develop Gilbert's syndrome.

GILBERT'S SYNDROME SYMPTOMS

Most patients with Gilbert's syndrome have no symptoms. The disorder is frequently diagnosed by coincidence when a lab test done for another reason (such as a life insurance examination) shows an abnormally high amount of unconjugated bilirubin.

When the level of unconjugated bilirubin rises beyond a certain point, the bilirubin pigment begins to discolor the whites of the eyes (making them appear light yellow). With even higher levels, the skin may also become yellow (jaundice). This potentially alarming appearance makes many people with Gilbert's syndrome see their healthcare provider.

Levels of bilirubin can fluctuate in people with Gilbert's syndrome. They may be highest after an infection (such as the flu), following periods of fasting, and after menstrual periods in some women. In addition, newborns with Gilbert's syndrome may have higher levels of bilirubin and more persistent jaundice than newborns without. (See "Patient information: Jaundice in newborn infants".)

Gilbert's syndrome may also become apparent when an affected person takes certain drugs that require the enzyme involved in bilirubin processing in the liver. A cancer drug called irinotecan is one example.

GILBERT'S SYNDROME DIAGNOSIS

The diagnosis of Gilbert's syndrome is suspected in people who have persistently slightly elevated levels of unconjugated bilirubin without any other apparent cause. A clinician may order several blood tests and possibly an ultrasound of the liver to make sure that there is no other cause of the high bilirubin levels.

Genetic testing can also confirm the diagnosis; however, genetic testing is not widely available and is generally not required.

GILBERT'S SYNDROME TREATMENT

No specific treatment is required for people with Gilbert's syndrome. However, there is an increased risk of side effects from certain drugs that are broken down by the liver (such as acetaminophen). Check with a healthcare provider before taking any new medications. Do not take more than the recommended amount of acetaminophen (Tylenol®).

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed every four months on our Web site (www.uptodate.com/patients).

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information

Patient information: Jaundice in newborn infants

Professional level information

Gilbert's syndrome and unconjugated hyperbilirubinemia due to bilirubin overproduction

The following organizations also provide reliable health information:

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• British Liver Trust

      (www.britishlivertrust.org.uk)

• The Canadian Liver Foundation

     (www.liver.ca/Liver_Disease/Adult_Liver_Diseases/Gilberts_Syndrome.aspx)

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