Liver Function Test (LFTs) is a group of tests that are performed together to detect, evaluate, and monitor liver disease or damage. The liver is one of the largest organs in the body and is located in the upper right-hand part of the abdomen and behind the lower ribs.
The liver metabolises and detoxifies drugs and substances that are harmful to the body. It produces blood clotting factors, proteins, and enzymes, helps maintain hormone balances, and stores vitamins and minerals. Bile, a fluid produced by the liver, is transported through ducts directly to the small intestine to help digest fats or to the gallbladder to be stored and concentrated for later use.
Liver function tests can be used to screen for liver infections, such as hepatitis, monitor the progression of a disease, such as viral or alcoholic hepatitis, and determine how well a treatment is working. It can also be used to measure the severity of a disease, particularly scarring of the liver (cirrhosis) as well as monitor possible side effects of medications.
Liver function test check the levels of certain enzymes and proteins in your blood. Levels that are higher or lower than normal can indicate liver problems. They include;
- Alanine transaminase (ALT) : ALT is an enzyme found in the liver that helps your body metabolize protein. When the liver is damaged, ALT is released into the bloodstream and levels increase.
- Aspartate transaminase (AST) : AST is an enzyme that helps metabolize alanine, an amino acid. Like ALT, AST is normally present in blood at low levels. An increase in AST levels may indicate liver damage or disease or muscle damage.
- Alkaline phosphatase (ALP) : ALP is an enzyme in the liver, bile ducts and bone. Higher-than-normal levels of ALP may indicate liver damage or disease, such as a blocked bile duct, or certain bone diseases.
- Albumin and total protein : Albumin is one of several proteins made in the liver. Your body needs these proteins to fight infections and to perform other functions. Lower-than-normal levels of albumin and total protein might indicate liver damage or disease.
- Bilirubin : Bilirubin is a substance produced during the normal breakdown of red blood cells. Bilirubin passes through the liver and is excreted in stool. Elevated levels of bilirubin (jaundice) might indicate liver damage or disease or certain types of anemia.
- Gamma-glutamyltransferase (GGT) : GGT is an enzyme in the blood. Higher-than-normal levels may indicate liver or bile duct damage.
- L-lactate dehydrogenase (LD) : LD is an enzyme found in the liver. Elevated levels may indicate liver damage but can be elevated in many other disorders.
- Prothrombin time (PT) : PT is the time it takes your blood to clot. Increased PT may indicate liver damage but can also be elevated if you’re taking certain blood-thinning drugs, such as warfarin.
Normal blood test results for typical liver function tests include;
- ALT : 7 to 55 units per liter (U/L)
- AST : 8 to 48 U/L
- ALP : 45 to 115 U/L
- Albumin : 3.5 to 5.0 grams per deciliter (g/dL)
- Total protein : 6.3 to 7.9 g/dL
- Bilirubin : 0.1 to 1.2 milligrams per deciliter (mg/dL)
- GGT : 9 to 48 U/L
- LD : 122 to 222 U/L
- PT : 9.5 to 13.8 seconds
These results are typical for adult men. Normal results vary from laboratory to laboratory and might be slightly different for women and children. Your doctor will use these results to help diagnose your condition or determine treatment you might need.
If you already have liver disease, liver function test can help determine how your disease is progressing and if you’re responding to treatment.
Tips To Guard Against Liver Disease
Factors that may increase your risk of liver disease include;
- Heavy alcohol use.
- Injecting drugs using shared needles.
- Tattoos or body piercings.
- Blood transfusion
- Exposure to other people’s blood and body fluids.
- Unprotected sex.
- Exposure to certain chemicals or toxins.
Signs and Symptoms
Signs and symptoms of liver disease include:
- Skin and eyes that appear yellowish (jaundice).
- Abdominal pain and swelling
Swelling in the legs and ankles.
- Itchy skin.
- Dark urine color, Pale stool color, or bloody or tar-colored stool.
- Chronic fatigue.
- Nausea or vomiting
- Loss of appetite
- Tendency to bruise easily
You can prevent liver diseases by adhering to the following health tips
- Drink alcohol in moderation.
- Get help if you use illicit intravenous drugs, and don’t share needles used to inject drugs.
- Use a condom during sex.
- If you choose to have tattoos or body piercings, be picky about cleanliness and safety when selecting a shop.
- Get vaccinated. If you’re at increased risk of contracting hepatitis or if you’ve already been infected with any form of the hepatitis virus, talk to your doctor about getting the hepatitis A and hepatitis B vaccines.
- Use medications wisely. Take prescription and nonprescription drugs only when needed and only in recommended doses.
- Avoid contact with other people’s blood and body fluids. Hepatitis viruses can be spread by accidental needle sticks or improper cleanup of blood or body fluids.
- Take care with aerosol sprays. Make sure the room is ventilated, and wear a mask when spraying insecticides, fungicides, paint and other toxic chemicals. Always follow the manufacturer’s instructions.
- Protect your skin. When using insecticides and other toxic chemicals, wear gloves, long sleeves, a hat and a mask.
- Maintain a healthy weight. Obesity can cause nonalcoholic fatty liver disease.