Published: 18 Jun 2025

ICD9: 277.4      ICD10: E80.4      ICD11: 5C58.01

Gilbert's syndrome is a common, harmless liver condition in which the liver doesn't properly process bilirubin, a yellow pigment produced when red blood cells break down.
This leads to mildly elevated levels of bilirubin in the blood, causing jaundice (yellowing of the skin and whites of the eyes) in some people.

Here's a breakdown of key aspects:

Key Features:

Nonhemolytic Jaundice: The jaundice is NOT caused by excessive destruction of red blood cells (hemolysis). Instead, it's due to a problem with how the liver handles bilirubin.
Genetic Basis: It's an inherited condition, often caused by a mutation in the *UGT1A1* gene. This gene provides instructions for making an enzyme called UDP glucuronosyltransferase, which is essential for conjugating (processing) bilirubin in the liver.
Mild and Fluctuating: The jaundice is usually mild and may come and go. It's often triggered by stress, illness, dehydration, fasting, or menstruation.
Benign and Asymptomatic: Most people with Gilbert's syndrome are otherwise healthy and don't experience any other symptoms. In many cases, the condition is discovered incidentally during routine blood tests.
No Treatment Usually Needed: Because it's harmless, treatment is generally not necessary. The key is to understand the condition and manage triggers.

How Bilirubin is Normally Processed:

1. Red Blood Cell Breakdown: Red blood cells break down, releasing hemoglobin. Hemoglobin is broken down into bilirubin. This initial form of bilirubin is called "unconjugated" or "indirect" bilirubin.
2. Travel to the Liver: Unconjugated bilirubin is carried in the blood to the liver.
3. Conjugation in the Liver: In the liver, the enzyme UDP glucuronosyltransferase (made by the *UGT1A1* gene) attaches a sugar molecule (glucuronic acid) to the bilirubin. This process is called "conjugation." The result is "conjugated" or "direct" bilirubin.
4. Excretion: Conjugated bilirubin is water-soluble and can be excreted in bile, which goes into the intestines and eventually is eliminated in stool.

In Gilbert's Syndrome:

The *UGT1A1* gene mutation leads to a reduced amount of the UDP glucuronosyltransferase enzyme or a less efficient enzyme. This means the liver can't conjugate bilirubin as effectively, leading to a buildup of unconjugated bilirubin in the blood.

Symptoms (when present):

Jaundice: Yellowing of the skin and whites of the eyes (most common). It can be subtle and easily missed.
Fatigue: Some people report mild fatigue.
Abdominal Discomfort: Rarely, mild abdominal discomfort.

Diagnosis:

Blood Tests: Elevated unconjugated bilirubin level, especially after fasting.
Liver Function Tests: Usually normal, except for the bilirubin level.
Genetic Testing: Can confirm the diagnosis by identifying a mutation in the *UGT1A1* gene, but it's not always necessary.

Things to Remember:

It's not a liver disease: Gilbert's syndrome doesn't cause liver damage. It's a functional variation in how the liver processes bilirubin.
No special diet: There's no specific diet recommended for Gilbert's syndrome. Maintaining a healthy lifestyle and avoiding triggers is generally sufficient.
Medications: Some medications can be affected by Gilbert's syndrome, so it's important to inform your doctor about your condition. For example, some drugs that are metabolized by the same enzyme might be cleared from the body more slowly.
Prognosis: Excellent. Gilbert's syndrome doesn't shorten lifespan or cause significant health problems.

In summary, Gilbert's syndrome is a common, benign condition characterized by mild, fluctuating jaundice due to a reduced ability of the liver to process bilirubin. It's usually diagnosed with blood tests and requires no treatment in most cases. It's important to understand the condition and inform your doctor about it, especially when taking medications.