Gilbert’s syndrome is usually without symptoms. Patients with the condition may develop mild jaundice.
Usually the condition is diagnosed in the late teens or early twenties. Many patients suffering from this condition are unaware and it does not hamper their daily living in any manner.
However, mild albeit long standing jaundice may worry many patients and they may seek diagnosis of the condition. There may be fears about more serious disorders of the liver.
A confirmed diagnosis of Gilbert’s syndrome that usually requires no treatment allays these fears. Usually Gilbert’s syndrome is a chance finding that is detected on routine blood tests.
Thus for diagnosis of Gilbert’s syndrome steps taken include medical history, physical examination and so forth. (1-6)
Detailed medical history is taken, including past history of jaundice and family history of long standing jaundice or Gilbert’s syndrome.
This involves a thorough look at liver and gastrointestinal system. Jaundice can be detected clinically in the eyes, skin and oral mucous membranes.
Routine blood counts are prescribed. This can often indicate infectious liver diseases or other infections that may lead to raised white blood cell counts.
In Gilbert’s syndrome there is a normal Reticulocyte count. Reticulocytes are blood cells that go on to mature and form Red blood cells.
In case of jaundice due to increased breakdown of RBCs and thus increased production of bilirubin (called haemolytic anemia) the Reticulocyte count is raised.
A normal number of reticulocytes indicates Gilbert’s syndrome and absence of haemolytic anemia.
Liver function test
Liver function tests are ordered. Primarily a rise in unconjugated bilirubin is found in blood.
If the other parameters like conjugated bilirubin and liver enzyme levels (AST – Aspartate transaminase, ALT – Alanine transaminase and lactate dehydrogenase) are normal and there is elevation of unconjugated bilirubin, Gilbert’s syndrome is suspected.
Gilbert's syndrome patients tend to have total serum bilirubin levels from 17-100 μmol/L. Mean values are lower in women than in men.
Bilirubin levels can, however, fluctuate in Gilbert’s Syndrome and it is possible that they can be within the normal range over a long period of time making diagnosis difficult.
The bilirubin level is raised if the patient is fasted for around 48 hours or if a drug Nicotinic acid is given intravenously. This is diagnostic of unconjugated hyperbilirubinemia that occurs in Gilbert’s syndrome.
Liver biopsy involves taking a sample tissue from the liver using a long hollow needle. This test is not required to diagnose Gilbert’s syndrome.
However, if the clinical findings are inadequate and there is a confusion regarding diagnosis, this test may be prescribed to exclude other liver diseases.
If a normal liver is stained with specific dyes it is noted that UGT is present in all parts of the liver and especially high in concentration in a special zone 3 of the liver. This zone is considered to play a role in the excretion of bile acids.
In patients with Gilbert’s syndrome it is seen that staining for UGT is low all over the liver and a fait stain is detected in the zone 3 confirming low or insufficient UGT.
Urine contains lower levels of urobilinogen. There is no bilirubin in urine.
Although the disease is caused due to a faulty gene that codes for the UGT enzyme, there are no specific prescribed genetic tests to diagnose Gilbert’s syndrome.
Genetic tests looking at the UGT1A1 gene may however be used in the laboratory to confirm the diagnosis. This is not recommended routinely.
Another experimental tool is an immunohistochemical assay. Here a set of polyclonal antibodies against UDP-glucuronosyltransferase enzyme are made to react with the blood sample.
An antibody binds to its target protein (in this case the UGT enzyme). If the levels of the enzyme are low, it can be detected by assaying the amount of binding to the antibodies.
Ruling out other conditions
Other diagnosis that needs to be ruled out includes Crigler-Najjar syndrome type I and type II.