Abnormal liver biochemistry
Abnormal liver biochemistry is common and can be caused by many conditions. Significant acute changes in liver biochemistry require urgent assessment and diagnosis. Minor changes in liver biochemistry that persist over months are commonly seen in general practice. Abnormal liver biochemistry can be difficult to interpret and may be secondary to a nonhepatic cause (eg thyroid disease, bone disease, muscle disorders).
The predominant pattern of abnormal liver biochemistry, together with clinical assessment of the patient, may indicate the likely cause and direct further investigations and management. The more common patterns of abnormal liver biochemistry are elevated hepatocellular enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST]) and elevated cholestatic enzymes (alkaline phosphatase [ALP], gamma-glutamyl transpeptidase [GGT]).
In patients with persistently abnormal liver biochemistry, exclusion of significant liver fibrosis or cirrhosis is important.
Initial assessment of a patient with abnormal liver biochemistry should include a detailed medical and medication history, physical examination and blood tests (see Initial assessment of a patient with abnormal liver biochemistry).
Medical history, including:
- medications—including prescription and over-the-counter drugs (particularly paracetamol), recreational drugs, herbal or dietary supplements (see Drug-induced liver injury for more detail)
- alcohol intake
- risk factors for nonalcoholic fatty liver disease (eg overweight/obesity, type 2 diabetes, other cardiovascular risk factors)
- risk factors for viral hepatitis, syphilis
Physical examination
- body mass index (BMI) and waist circumference
- stigmata of liver disease, such as spider naevi and palmar erythema
Blood tests
- liver biochemistry
- full blood count
- international normalised ratio (INR)
Red flags that require urgent liver ultrasound or computed tomography (CT) scan and urgent specialist referral are:
- signs of liver synthetic dysfunction (eg jaundice, hypoalbuminaemia, elevated international normalised ratio [INR])
- hepatic encephalopathy (eg impaired concentration, disturbed sleep patterns, cognitive deficits, disorientation, slurred speech)
- suspected malignancy (eg weight loss, marked cholestasis).
It is difficult to make general recommendations for further investigations and referral in patients with abnormal liver biochemistry because these will vary depending upon the pattern, magnitude and duration of the abnormal liver blood tests, and factors such as patient age, BMI, comorbidities, alcohol intake and medications. International guidelines on the management of abnormal liver blood tests have been published1.
Persistently abnormal liver biochemistry requires further investigation and consideration of referral to a specialist. Consult local guidelines for referral requirements in your area.