Gilbert Syndrome: What It Means, Symptoms and Outlook

Gilbert syndrome is an inherited condition that changes how the liver handles bilirubin. Bilirubin is a yellow substance made when old red blood cells break down^1,5.

Approximately one-third of affected people have no symptoms. Others notice mild yellowing of the skin or eyes at times. This yellowing is known as jaundice.

The condition does not cause liver injury or lead to end-stage liver disease³. However, fasting, illness, dehydration, and stress may make jaundice more noticeable.

Certain medicines may also pose added risks. This guide covers the causes, signs, diagnosis, treatment, medicine concerns, and long-term outlook.

Gilbert syndrome is a common genetic condition that affects bilirubin processing in the liver. It causes mild, changing levels of unconjugated bilirubin in the blood.

Unconjugated bilirubin is the form that the liver has not yet processed^2,5. Other liver test results are usually normal^2,3.

Old red blood cells release bilirubin as they break down^1,5. This yellow substance travels through the blood to the liver.

The liver changes unconjugated bilirubin into conjugated bilirubin⁵. Conjugated bilirubin is a processed form that dissolves in water^5,10.

The body can then move it into bile⁹. Bile carries the processed substance from the liver into the intestines. It then leaves the body in stool.

A small amount of bilirubin normally remains in the blood. Gilbert syndrome slows one step in this removal process^1,5.

UGT1A1 is the gene that provides instructions for a liver enzyme that processes bilirubin^5,10. An enzyme is a protein that helps a body process take place.

People with this condition may have about 30% of normal UGT1A1 activity^1,5. That lower activity slows the processing of unconjugated bilirubin⁵.

The slower process allows a small amount to build up in the blood⁵. Bilirubin levels may rise and fall instead of staying at one level.

Mild jaundice may appear when the level rises. The liver otherwise keeps working as expected in most affected people^2,3.

This blood test pattern differs from patterns linked with many liver diseases. Those conditions may affect liver enzymes or raise both forms of bilirubin.

Changes in the UGT1A1 gene cause Gilbert syndrome^1,5. This gene provides instructions for making the enzyme that processes bilirubin⁵.

The gene change is present from birth^7,9. However, the condition often remains unnoticed until the teen years or later⁹.

Some cases are discovered during a blood test done for another reason. The test may show raised bilirubin despite normal results elsewhere^2,3.

Many cases follow an autosomal recessive inheritance pattern^1,2,5. This means both gene copies in each cell have the change⁵.

Each parent often carries one changed copy in this pattern⁵. The parents usually do not show signs of the condition⁵.

However, inheritance can vary with the exact UGT1A1 change⁵. Some changes follow an autosomal dominant pattern⁵. In that pattern, one changed gene copy can be enough⁵.

The types of UGT1A1 changes also vary among populations⁵. Not everyone with a related gene change develops raised bilirubin⁵.

Family history can still provide useful details during an assessment. Yet many affected people appear to be the only known case in their family.

Gilbert syndrome symptoms are absent in many affected people. Some people only learn about the condition through routine blood work.

The main sign is occasional mild jaundice. If jaundice occurs, the skin or whites of the eyes may look yellow.

The yellow color comes from a rise in blood bilirubin^7,9. These changes may be easier to see in the eyes.

About 30% of affected people have no signs or symptoms⁵. Their raised unconjugated bilirubin may only appear during blood testing⁵.

Jaundice may come and go throughout life⁴. It often fades as bilirubin falls again. Episodes usually have no harmful effects.

Gilbert syndrome triggers often place stress on the body^1,5. The following events may raise bilirubin or make jaundice easier to notice:

Triggers can differ between affected people. Tracking meals, illness, exercise, and jaundice may help you notice a pattern.

Some affected people report fatigue, weakness, nausea, or diarrhea. Others report stomach discomfort or tiredness⁵.

Research has not shown that mild raised bilirubin causes these symptoms. Their cause may remain unclear.

Do not assume that each new symptom comes from this condition. If symptoms continue or become troubling, discuss them with a healthcare professional.

A clinician may suspect Gilbert syndrome after unexplained jaundice or a raised bilirubin result. Diagnosis depends on a matching test pattern and the exclusion of other causes.

The usual finding is a mild rise in unconjugated bilirubin^2,3. This rise often appears without other abnormal liver test results^2,3.

The conjugated bilirubin level is generally normal⁴. Blood counts are also part of the usual assessment.

Bilirubin levels can change over time. Therefore, a past normal level does not rule out the condition.

A clinician may review older records for earlier bilirubin increases. A history of repeated, isolated increases can support the diagnosis.

The clinician may also ask about common triggers. These include illness, fasting, dehydration, menstruation, and hard exercise.

A full medicine history is important during this review. Some drugs can affect bilirubin processing or cause liver injury.

Jaundice has many possible causes. Clinicians must consider those causes before confirming Gilbert syndrome.

Hemolysis can also raise unconjugated bilirubin. Hemolysis means red blood cells break down faster than expected.

This process releases more bilirubin into the blood. A blood count and other tests can help assess red blood cells^3,6.

Clinicians also consider medicine effects during the assessment. Some drugs reduce bilirubin processing, while others may harm the liver.

Liver and bile system disorders may raise the conjugated part of bilirubin. That result differs from the usual Gilbert syndrome pattern.

Viral, immune, and metabolic liver diseases may also need consideration. The needed tests depend on the person’s history and test results.

A compatible blood pattern alone does not explain every type of jaundice. A clinician uses the full picture before making the diagnosis.

Most people do not need genetic testing for Gilbert syndrome^4,6. Blood counts, liver tests, and bilirubin results are often enough.

A genetic test can confirm a change in UGT1A1. It may help when the findings are unusual or unclear.

Testing may also help distinguish this condition from Crigler-Najjar syndrome. That inherited disorder also involves changes affecting UGT1A1.

Crigler-Najjar syndrome causes more severe and lasting jaundice. Some results may overlap with its less severe form.

In those cases, finding the exact gene change may clarify the diagnosis. This distinction matters because Crigler-Najjar syndrome can be more serious.

Gilbert syndrome treatment usually consists of reassurance and observation. Medicine is not generally needed because the condition does not injure the liver³.

Bilirubin levels may rise and fall without treatment. Mild jaundice often clears on its own and causes no harmful effects.

The condition does not cause serious long-term health problems^8,9. Treatment is therefore not needed for the bilirubin change itself.

Follow-up may still be useful if the test pattern changes. A clinician can reassess new jaundice or symptoms that do not fit the usual pattern.

Managing known Gilbert syndrome triggers may make episodes less likely. The following steps focus on triggers found in the source evidence:

Stress control options may include exercise, meditation, or music. However, strenuous exercise can raise bilirubin in some affected people.

These steps do not change the inherited gene. They aim to reduce events that can raise bilirubin.

UGT1A1 helps the body process some medicines. Lower enzyme activity may raise the risk of side effects or drug toxicity.

Tell each healthcare professional about the diagnosis before starting a new medicine. This information is especially important before treatment with irinotecan.

Irinotecan is a cancer chemotherapy medicine. Its active breakdown product can build up when UGT1A1 activity is low.

That buildup can cause diarrhea and reduced blood cell production. A cancer specialist can consider this risk while planning care.

Atazanavir and indinavir can block UGT1A1 activity. These antiviral medicines may cause higher bilirubin levels.

This concern does not mean that every medicine will cause problems. Talk with a healthcare professional before taking a new medicine.

The Gilbert syndrome prognosis is excellent^2,3. Affected people can lead long and healthy lives⁹.

Gilbert syndrome does not cause progressive liver injury³. It also does not lead to end-stage liver disease³.

Most affected people need no ongoing treatment. They also do not develop serious long-term problems from the condition^8,9.

Mild jaundice may still appear at times⁴. Illness, fasting, dehydration, stress, or another trigger may bring on an episode.

The yellow color can be unsettling. However, jaundice linked with this condition is generally mild⁴.

Gilbert syndrome usually causes isolated unconjugated bilirubin with normal liver tests^2,3. Other liver diseases may affect both bilirubin forms or liver enzymes.

Severe or lasting jaundice is not the usual pattern. A known diagnosis should not be used to explain every new episode.

Crigler-Najjar syndrome causes more severe and persistent jaundice. Other liver and bile disorders can produce different blood test patterns.

Jaundice has several possible causes, so a new episode deserves medical review. Contact a healthcare professional in these situations:

Do not automatically blame these signs on Gilbert syndrome. A clinician can check whether another condition may explain them.

Gilbert syndrome is a mild inherited difference in bilirubin processing. Reduced UGT1A1 activity causes changing levels of unconjugated bilirubin^1,5.

Most affected people have no symptoms or only mild jaundice at times. Regular meals and good fluid intake can address two common triggers.

The outlook is excellent, with no progressive liver injury^2,3. Still, tell healthcare professionals about the diagnosis before taking new medicines.