Different Liver Function Tests and What They Mean

Different Liver Function Tests and What They Mean
December 28, 2012 12:23 PM

Your liver’s job is great, as it carries out many excretion, detoxification and synthetic functions. Only a few of these can actually be measured by the levels of certain products in your blood, however.

Liver function tests, or LFTs, are what measure the different enzymes and proteins which are in your blood that are released when liver cells get damaged or are made by liver cells. These tests are performed when liver disease of some sort is suspected. The results can show your doctor what type of liver disease is present so they know how to proceed further. Lab tests for liver function can show how badly your liver is damaged and will also monitor your reaction to drugs or other treatments.

Different Liver Function Tests

There are many different types of liver enzyme labs, and your doctor might order all of these tests to be ran together using just one blood sample. This is called a liver panel.

Albumin – This is a protein which is only made by liver cells, so its concentration shows liver synthetic function. It will stay in your blood for a long time so if there are changes in the levels of albumin it shows a liver disease that is long-standing. Normal values for albumin should be between 35 and 50 g/L. If you are malnourished, this can also decrease albumin, since there is not enough protein which is absorbed into your body. Loss of albumin into the urine can occur from kidney damage and low levels of albumin will cause peripheral oedema, normally seen as swelling of the ankles because of the low levels of proteins and salts in your blood.

Total Proteins – These levels should be between 63 and 80 g/L and they show the synthetic functions of your liver. These liver function tests measure all the protein types which are circulating in your blood. With very severe liver disease, your liver isn’t able to make the right amount of blood proteins.

Gamma Glutamly Transpeptidase –The GGT enzyme can be found in certain cells of your liver and also in cells of the bile duct. It will be elevated in diseases which obstruct or lessen the flow of bile. Warfarin, a blood thinner, alcohol abuse and epilepsy drugs can all increase levels of GGT. It has been used to find chronic alcohol abuse, but since GGT is increased in many different conditions it is not an accurate way to detect this. Your GGT levels shouldn’t be under 60 U/L.

Alkaline Phosphatase – ALP is usually found in the small bile tracts of your liver and is mostly implicated in the diagnosis of biliary obstruction. Elevated levels could be from a problem outside the liver such as cancer since there are so many types of this enzyme found in the bone, placenta and liver. Normal levels should be between 35 and 50 g/L.

Bilirubin – This is made from the breakdown of the red blood cells in your body. Your liver is generally in charge of detoxification of bilirubin and the excretion of it into bile. A raise in the overall level of bilirubin will make a condition known as jaundice. People with jaundice have a complexion that is yellowish, and it will affect the whites of their eyes as well. You can also see an increase in bilirubin levels from other conditions which cause an increased breakdown of red blood cells. Normal ranges for bilirubin should be under 20 umol/L.

Ammonia – A by-product of protein metabolism, ammonia is made by bacteria in your large intestine. Your liver is in charge of the detoxification of ammonia by changing it to urea. You will sometimes see ammonia levels measured in your blood to get more information about your liver function and the presence of encephalopathy. Ammonia blood levels can also correlate poorly with these situations, so any measurements of ammonia has its limitations. The reference values for ammonia tend to widely vary in different labs.

Alanine Amino Transferase and Aspartate Amino Transferase – Both of these enzymes are great markers of damage to your liver cells which happens in disorders like viral hepatitis. Found in the cardiac muscle, liver, kidneys, brain, skeletal muscle, lungs, pancreas, red blood cells and white blood cells, you can see AST all over your body, yet ALT is generally found only in your liver. Both of these usually show low levels in your blood so when your liver cells are damaged you can expect some of them to leak into your blood and raise the levels. Just about any injury to liver cells can raise the levels of these enzymes, but they won’t necessarily show how badly your liver is damaged. Values for ALT should be under 36 U/L and levels for AST should be under 42 U/L.

Restoring Liver Function to Normal

Once you have been through all the liver enzyme labs, your doctor can help you decide the next step in your treatment. You should firstly take any medication that your doctor prescribes you. With problems such as hypothyroidism, mononucleosis, inflammation, a gallbladder infection or pancreatitis, your doctor could prescribe you anti-inflammatories or antibiotics.

If you do any regular drinking or if you smoke, cut these both out or reduce them to a very minimum. Both of these contain toxins that are bad for your liver, especially when the liver enzymes are raised already. Alcohol can also raise fat accumulation in your liver.

Take the supplements known as milk thistle. Although results are varied, this herb does show promising results in the treatment of liver disease and viral hepatitis. You can take the capsules as indicated on the label because it will vary between different brands.

If you are overweight, lower your over caloric intake. An excess of calories, especially when it’s from carbohydrates, will make your liver enzyme levels worse by raising fat deposits. Get rid of all the sweets in your diet first. Then focus on food choices that are healthier such as fruits, vegetables, whole grains and lean proteins.

Although finding out you have any type of liver disease can be scary, working with your doctor to figure out the best plan of treatment for you can help you return your liver function to normal. Liver function tests will start you off so you can understand exactly what is wrong, and then decide on treatments from there.

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Written by: Michal Vilímovský (EN)
Education: Medical student, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic
Published: December 28, 2012 12:23 PM
Next scheduled update: December 28, 2014 12:23 PM
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