Buku Medicine

Introduction

Patients have liver function tests checked for a variety of reasons both in the community and in hospital settings. Liver tests can be acutely or chronically deranged and can be abnormal for a number of reasons. A ‘liver screen’ is commonly requested to investigate abnormal liver functions tests. The screen can be modified depending on the age of the patient and whether acute or chronic liver disease is suspected.  

A careful history is vital. Salient points in the history should be: 

  • Specific symptoms/signs (jaundice, abdominal pain, weight loss, pruritus etc) 
  • Comorbidity 
  • Personal or family history of liver disease 
  • Personal or family history of autoimmune disease 
  • Alcohol – pattern of consumption, including volume and duration  
  • Risk factors for viral hepatitis (injecting drug use, tattoos, blood transfusions and lived or had medical treatment in a country where viral hepatitis is endemic) 
  • Medication history for the past 6 months including antibiotics, over the counter and herbal remedies and recreational drugs 

A thorough examination should include: 

  • Signs of chronic liver disease 
  • Jaundice 
  • Hepatic flap 
  • Palmar erythema 
  • Spider naevi 
  • Ascites 
  • Splenomegaly 
  • Evidence of decompensation (jaundice, ascites, hepatic encephalopathy) 

It is useful to look at the pattern of abnormal liver function tests to see if they are predominantly hepatitic, cholestatic or there is hyperbilirubinaemia. Sometimes there is a mixed pattern. The pattern of abnormality in the liver function tests can help guide investigations.  

 

References 

  • Newsome P et al.  Guidelines on the management of abnormal liver blood tests.  Gut 2018; 67:6-19

Hepatitic LFTs

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Cholestatic LFTs

Cholestatic liver tests will show a predominant rise in alkaline phosphatase +/- a rise in bilirubin. Alkaline phosphatase (ALP) originates from bone and liver and it is important to understand this. Checking gammaglutamyl transferase (GGT) can be useful as this will be raised in liver but not bone causes of a raised ALP. Some laboratories can do ALP iso-enzymes which can differentiate liver / bone origin. 

Liver causes of cholestatic liver tests are: 

Extra-hepatic biliary obstruction 

  • Gallstones 
  • Malignancy (pancreatic cancer / cholangiocarcinoma / metastatic disease) 

Primary Biliary Cholangitis (PBC) 

  • Autoimmune liver problem associated with positive anti-mitochondrial antibody (AMA) and raised IgM 
  • Inflammation and scarring of the small intra-hepatic bile ducts 
  • Female:male ratio of 10:1 

Primary Sclerosing Cholangitis (PSC) 

  • Inflammation and scarring of the intrahepatic and or extrahepatic bile ducts 
  • Usually associated with inflammatory bowel disease 

Medications 

  • A number of medications can cause cholestatic liver tests which include 
  • Antibiotics: flucloxacillin, co-amoxiclav 
  • Anabolic steroids 
  • Oral contraceptive pill 

Others 

  • Hepatic congestion (e.g. cardiac failure) 

Hyperbilirubinaemia

Jaundice is caused by accumulation of bilirubin in the bloodstream. It becomes apparent when there is deposition in the skin, sclera and mucous membranes. The causes of jaundice can be divided into: 

Prehepatic 

  • Predominantly unconjugated bilirubin 
  • Causes: 
  • Haemolysis (see haematology section on haemolysis) 
  • Gilberts syndrome – impaired conjugation of bilirubin 

Hepatic 

  • Acute liver injury 
    • Viral hepatitis (A,B,C and E), CMV and EBV 
    • Drug induced liver injury 
    • Alcoholic hepatitis 
    • Ischaemic hepatitis 
    • Vascular liver disease – eg Budd-Chiari syndrome 
    • Autoimmune hepatitis 
  • Chronic liver disease of any aetiology – either by progressive disease or decompensation 

Post-hepatic  

  • Gallstones causing obstruction 
  • Malignancy – cholangiocarcinoma, pancreatic cancer, liver metastases or lymphoma 
  • Bile duct strictures – benign or malignant 
  • Cholangitis   

 

Isolated raised bilirubin 

  • This is most commonly cause by Gilbert’s syndrome, which affects 5-8% of the population.   
  • To diagnose Gilbert’s:  Repeat Liver blood tests on a fasting sample with an FBC and direct and indirect bilirubin. The total bilirubin should rise further, owing to the indirect component, and there should be no evidence of anaemia. If the patient is anaemic, haemolysis needs to be excluded  
  •  This is a benign condition and does not need referral