Gilbert's syndrome is a liver disease, benign and hereditary, characterized by a variable increase of the bilirubin level in the blood (hyperbilirubinemia).
People who suffer from Gilbert's syndrome has a bilirubin level in the blood between 2 and 4 mg/dl that usually increases with fasting, menstruation, insomnia and viral infections.
Bilirubin is a brownish yellow pigment considered as a waste product. Bilirubin has antioxidant activity and gives the feces their characteristic brown color.
Most part of the bilirubin produced each day comes from the breakdown of the hemoglobin present in the red blood cells (RBCs). This type of bilirubin is called unconjugated or indirect bilirubin. Later, bilirubin is converted in the liver from unconjugated to conjugated bilirubin (or direct bilirubin) when glucoronic acid is added making it water-soluble.
The Gilbert's syndrome is a disorder of the bilirubin metabolism where there is an increase in the unconjugated bilirubin in the blood.
Gilbert's syndrome is a genetic and congenital disorder. It is inherited as autosomal dominant or recessive.
The main cause is a mutation in the UGT1A1 gene located in chromosome 2 (2q37.1). This gene encodes the uridine diphosphate glucuronosyltransferase responsible for the conjugation of bilirubin and endogenous hormones.
The 30% of patients has also problems in the transport of other organic anions. In addition, half of the patients show hemolysis (premature destruction of red blood cells).
Gilbert's syndrome affects around 2% to 7% of individuals in the general population.
It usually becomes apparent in the adolescence and it is more common in males than in females (male-to-female ratio between 2 to 7).
Most patients are usually asymptomatic (they have no symptoms) because there is only a mild hyperbilirubinemia (a slight increase in bilirubin levels).
Sometimes, there are present symptoms related to the increase of bilirubin in the blood such as:
Jaundice in Gilbert's syndrome may be triggered by:
The diagnosis of Gilbert syndrome is suspected in patients who have persistently slightly elevated levels of unconjugated bilirubin (particularly after fasting, menstruation or vigorous exercise) without hemolysis or any other apparent cause.
In a blood test, there is a mild increase of unconjugated bilirubin, 2 or 3 times over the normal range. The total bilirubin does not usually exceed 6 mg/dl in any case.
To confirm the diagnosis, it is possible to perform the nicotinic acid provocation test that produces further rise in the serum bilirubin in around three hours. This test is not usually needed in clinical practice.
No specific treatment is required for Gilbert's syndrome. It is a benign disorder with no long-term effects.
Only when the pain or the jaundice persist is necessary to prescribe a treatment.
Some drugs, such as phenobarbital, clofibrate or glutetimetide may reduce the bilirubin level in the blood, whereas the nicotinic acid (B3 vitamin) may increase it.
Irinotecan must not be administered to people with Gilbert's syndrome. Irinotecan is an antineoplastic chemotherapy drug that increases the risk to suffer hematologic toxicity.
To prevent jaundice it is necessary to avoid:
People with Gilbert's syndrome have a normal life expectancy; it is a benign disorder.