Liver function tests explained:
It’s important to note that every child will have their own ‘normal’ and whilst these levels are a guide, it doesn’t necessarily mean a result outside of these ranges is dangerous. Always talk to your child’s medical team if you have any worries about test results. LFTs show the amount of inflammation in the liver, whether the bile ducts are affected and how well the liver is functioning.
| Name of test |
Normal range |
What does this show? |
| Bilirubin (SBR)
a) Total bilirubin
b) Conjugated bilirubin |
a) 3 – 20 mmol/l
b) Conjugated less than 7 mmol/l |
The total bilirubin level corresponds to the level of jaundice present.The amount of conjugated bilirubin compared to the unconjugated bilirubin can show whether jaundice is caused by red blood cells breaking up too quickly (not a liver disease) or is due to a reduced flow of bile out of the liver.
Conjugated means that a sugar has been added to the bilirubin. |
| Aspartate Aminotransferase (AST) |
10 – 40 IU/I |
High levels can mean there is liver inflammation present. |
| Alanine Aminotransferase (ALT) |
| Gamma-Glutamyl Transferase
(GGT, gGT or Gamma GT) |
5 – 55 IU/L |
High levels can mean bile duct inflammation or obstruction.The results can sometimes give information about bile production. |
| Alkaline Phosphatase (ALP) |
Less than 350 IU/L |
High levels can mean there is bile duct inflammation
BUT
ALP is not specific to the liver as it is also produced in other organs e.g. bones. Therefore, abnormal levels can be due to processes occurring in other parts of the body. |
| Total Protein |
60 – 80 g/l |
High and low levels can be used in consideration with the other LFT results |
| Albumin |
35 – 50 g/l |
Low levels can mean the liver is not making enough, that protein is being lost through the stool or a child is not well nourished. |
Another blood test which is helpful to assess how the liver is working is a blood clotting test. Blood is taken, chemicals are added to it in the lab and the time taken for blood to clot is measured.
| Name of test |
Normal range |
What does this show? |
| Blood Clotting (Coagulation) Test
a) PT (Prothrombin time)
b) INR (International normalised ratio*)
*INR is a standardised version of the PT for comparison, they both measure the same thing |
a) 12 – 15 seconds
b) 0.9 – 1.2 |
The liver produces substances needed for blood to clot.Raised levels can mean there is less Vitamin K due to a reduced bile flow.
If Vitamin K is given and the result is still raised, it may mean there is damage to the liver. |
Other blood tests include:
| Name of test |
What is measured? |
| Full blood count (FBC) |
Haemoglobin (Hb)White blood cell count (WBC)
Platelets (Plt) – levels can fall in liver disease if the spleen is enlarged. |
| Urea and electrolytes |
Urea and creatinine are waste products removed by the kidneys.Electrolytes include sodium, chloride and calcium. |
| Blood glucose |
A high or low level of sugar in the blood can sometimes be a sign of liver damage or a metabolic liver disease. |
| Ammonia |
Ammonia is a waste product. It is converted into urea in the liver and is then removed in urine.A higher level than usual may mean there is damage to the liver or an underlying metabolic condition. |
Some of these tests may be used to monitor the effects of medications on the body.
This website provides general information but does not replace medical advice. It is important to contact your/your child’s medical team if you have any worries or concerns
