Key:
NILS = Hep B and C serology, Autoimmune profile, ferritin, Transferrin saturation, USS liver
NAFLD = non alcoholic fatty liver disease
Mildly abnormal liver function tests are a common and often incidental finding. In the absence of jaundice or symptoms suggestive of biliary or hepatic disease, mild to moderate elevation in the ALT 40 - 200 or the ALP 110 – 250 usually requires investigation, but only on a routine basis. Gamma GT is a very sensitive biochemical marker and an isolated elevation in this does not usually require further investigation. The ALT primarily reflects hepatocellular inflammation whilst the alkaline phosphatase often reflects biliary disease or obstruction. However, there is a considerable overlap in the degree of elevation of both these enzymes in both hepatocellular and obstructive disease.
The detection of mild elevation in the ALT (less than 80u/l or an alkaline phosphatase less than 150u/l) in an asymptomatic patient may not require further investigation if a clear precipitant (e.g obesity, excess alcohol intake or drugs) has been identified. Repeat LFT monitoring and review may be sufficent.
With a mild elevation in ALT or ALP without a clear precipitant or moderate elevation in the ALT (i.e. greater than twice the upper limit of normal > 80u/l or an alkaline phosphatase greater than 150u/l) a non-invasive liver screen should be performed:
- ultrasound scan of the liver and biliary tree
- hepatitis B and C serology
- autoimmune screen (including antinuclear antibodies with anti-smooth muscle antibodies)
- serum ferritin and transferrin saturation
- thyroid function and serum glucose
In young patients with progressive liver disease check serum copper and caeruloplasmin and alpha 1 antitrypsin but these are not routine investigations.
1. alcohol
2. hepatic steatosis/non alcoholic steato-hepatitis
3. drugs or medication
4. chronic viral hepatitis (B and C)
5. obstructive biliary disease eg gallstones
6. infiltrative diseases of the liver
7. autoimmune hepatitis
- These investigations reveal a cause for liver test abnormalities in approximately 80 to 90% of patients. In this remaining 10 to 20% of patients we then need to decide whether these patients should undergo a liver biopsy. Most gastroenterologists consider performing a liver biopsy when there is a persistent (e.g. greater than six months) elevation in the ALT greater than twice the upper limit of normal. However, if there is a strong indication that the ALT abnormality is due to alcohol or fatty liver and patients should attempt a period of abstention or weight loss to assess whether there is any improvement in the liver function test before liver biopsy is performed. The diagnoses made after liver biopsy in this group of patients is as follows: 34% non-alcoholic steato-hepatitis (NASH), 32% had simple fatty liver, 9% cryptogenic hepatitis and drug related liver damage in 8%. Only 2% had an autoimmune hepatitis. (Skelly et al Journal Hepatology 2001).