Gamma Glutamyl Transferase Activity in Gilbert's Disease

Category: Hepatology

Gilbert's disease (GD), an isolated non-haemolytic unconjugated hyperbilirubinaemia occuring in 8% of the population, is diagnosed by estimating serum unconjugated bilirubin level. GD is under diagnosed leading to inappropriate expensive and invasive Investigation. A patient with congenital hyperbilirubinaemia was noted to have low gamma glutamyl transferase (gGT) activity. A prospective study has been undertaken to determine if low gGT is a marker for unconjugated hyperbilirubinaemia. The gGT and bilirubin results of random blood samples sent for liver function tests to the Clinical Biochemistry Department were abstracted and entered into a database.

Results: Results were stratified according to bilirubin level (mmol/l), group 1) 20–10, n=163– normal liver biochemistry and probable GD; group 2) 20–100, n=44– abnormal liver biochemistry; group 3) 16–17, n=113; group 4) 3=216. The following gGT activities [U/l mean (SD)] were found: Group 1: 18.7 (12), Group 2: 120 (335), Group 3: 35 (104), Group 4: 25 (98). gGT in Group 1 is significantly lower than all other groups. G1: G2, G3, G4 p<0.002.

Thus, low gGT activity is associated with isolated hyperbilirubinaemia.