What is Gilbert's syndrome?

Question

Found in blood test.

Answer 1

Gilbert's syndrome (pr. Zhil-bear), often shortened to the acronym GS, is the most common hereditary cause of increased bilirubin, and is found in up to 5% of the population. The main symptom is otherwise harmless jaundice which does not require treatment, caused by elevated levels of unconjugated bilirubin in the bloodstream (hyperbilirubinemia).

The source of this hyperbilirubinemia is reduced activity of the enzyme (glucuronyl transferase) which conjugates bilirubin and some other lipophilic molecules. Conjugation renders the bilirubin water-soluble and suitable for excretion via the kidneys.

Gilbert's syndrome was first described by French gastroenterologist Augustin Nicolas Gilbert and co-workers in 1901.[1]

Pathogenesis
Gilbert's syndrome is caused by approximately 30%-50% reduced glucuronidation activity of the enzyme Uridine-diphosphate-glucuronosyltransferase isoform 1A1 (UGT1A1).[2][3] The gene which encodes UGT1A1 normally has a promoter region TATA box containing the allele A(TA6)TAA. Gilbert's syndrome is associated with homozygous A(TA7)TAA alleles.[4] The allele polymorphism is referred to as UGT1A1*28.


[edit] Signs and symptoms
Gilbert's syndrome produces an elevated level of unconjugated bilirubin in the bloodstream but normally has no serious consequence. Mild jaundice may appear under conditions of exertion, stress, fasting, and infections.

Some patients report experiencing unpleasant physical symptoms during episodes of high bilirubin levels. They may report meal-related fatigue, tremors, nausea, and abdominal pain, with jaundice.[5] Because patients may be unaware of their condition but conscious of apparent jaundice, they may present these symptoms at urgent-care facilities needlessly.

Gilbert's syndrome also reduces the liver's ability to detoxify certain drugs. For example, Gilbert's syndrome is associated with severe diarrhea and neutropenia in patients who are treated with irinotecan, which is metabolized by this enzyme.[6]

While paracetamol (acetaminophen) is not metabolized by UGT1A1[7], it is metabolized by one of the other enzymes also deficient in most people with GS[8]. Metabolism of paracetamol is thus reduced by 31%[9], leaving liver-toxic metabolites in the body for longer periods.


[edit] Diagnosis
While this syndrome is considered harmless, it is clinically important because it may be confused with much more dangerous liver conditions. However, these will show other indicators of liver dysfunction. Hemolysis can be excluded by a full blood count and lactate dehydrogenase levels. Liver biopsy is rarely necessary. The onset of GS is often in childhood or early adulthood.

Normal levels of total bilirubin (conjugated and unconjugated) are under 20 mmol/dl. Patients with GS show only elevated unconjugated bilirubin, while conjugated is in normal ranges and forms less than 20% of the total. Levels of bilirubin in GS patients should be between 20 mmol/dl and 80 mmol/dl (divide by 16 to express these numbers in mg/L). GS patients will have a ratio of unconjugated/conjugated (indirect/direct) bilirubin that is commensurately higher than those without GS. Other liver enzymes are expected to be similar between patients with and without GS. Complete liver enzyme tests are ordered in order to assure the correct diagnosis.

The level of total bilirubin is often increased if the blood sample is taken while fasting.

More severe types of gluconitril transferase disorders like GS are Crigler-Najjar syndrome (types I and II). These are much more severe and cause brain damage in infancy (type I) and teenage years (type II).

Answer 2

"Familial nonhemolytic jaundice". In other words, it is jaundice (turning yellow due to liver issues) which does not happen because of the destruction of red blood cells, and it runs in families.

Answer 3

An inherited liver disorder