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CPD: Key questions on abnormal LFTs

Key questions on abnormal liver function tests

GPwSI in gastroenterology Dr Robert B Palmer answers key questions on primary care assessment and management of patients with abnormal liver function test results (LFTs)

Liver function tests (LFTs) are commonly used in primary care to investigate potential liver injury or disease, but choosing the right tests and interpreting findings to guide further management can be complex.

This learning module will take you through key questions on abnormal LFTs to understand:

  • How to deal with isolated raised bilirubin levels
  • Investigation and of raised alanine transanimase (ALT) and what to include in a liver screen
  • Diagnosis and management of non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD)
  • Appropriate investigation and management of raised alkaline phosphatase (ALP), both isolated and in combination with raised ALT
  • How to manage abnormal LFTs due to statins and other medications

Q The finding of an isolated raised bilirubin is quite common and is usually taken to suggest Gilbert’s syndrome. How can we reassure ourselves that this is the case – and what are the clinical implications of this?

A A raised bilirubin, with otherwise normal LFTs, is very likely to be caused by Gilbert’s syndrome, which is thought to affect over one in 20 of the population. Gilbert’s is an inherited (usually autosomal recessive) metabolic disorder characterised by a mild and intermittent elevation of unconjugated (indirect) bilirubin levels, due to defective conjugating enzymes in the liver. Gilbert’s does not progress to chronic liver disease, and life expectancy is normal.

A bilirubin level <50 µmol/l in an asymptomatic patient with otherwise normal LFTs is unlikely to be clinically significant, and further investigations are probably not indicated if below this level, though levels higher than this may still be attributable to Gilbert’s (usually <85 µmol/l).1 If the bilirubin result is towards the higher end of normal, it may be worth repeating a blood test in three to six months to ensure it hasn’t worsened.

Other causes that should be considered with bilirubin levels >50 µmol/l include haemolysis (including autoimmune haemolytic anaemias, hereditary spherocytosis and sickle cell disease), other genetic causes (such as Crigler-Najjar syndrome and Dubin-Johnson syndrome) and drugs (methyldopa, sulfasalazine, carbimazole and rifampicin). To investigate further, test for paired unconjugated/conjugated bilirubin levels, FBC, blood film, LDH and reticulocytes to determine the most likely cause (see table 1).

Blood resultSignal
Mostly unconjugated bilirubin (>70%), no haemolysisLikely Gilbert’s syndrome
Mostly unconjugated bilirubin (>70%), evidence of haemolysisHaemolysis
Mostly conjugated bilirubin (>50%)Rare (Dubin-Johnson, Rotor syndrome)
Table 1. Blood tests indicating causes of raised bilirubin

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Dr Robert B Palmer is a GPwSI Gastroenterology at Homerton Healthcare Trust, London

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Hany Hanna 2 April, 2022 9:12 pm