The liver is an important part of your body, playing many vital roles, such as the production of bile, the production of protein for blood plasma, the production of cholesterol, etc. There are numerous diseases and issues that could compromise liver health, such as liver fibrosis/cirrhosis, fatty liver, and even liver cancer.
To maintain a healthy liver, you first need to be aware of any potential abnormalities that can occur. For this purpose, a gastroenterologist may recommend that you get a liver function test. This is a commonly used diagnostic test that measures the types of substances produced by your liver to determine the type of abnormality and where it occurs in the liver. In this article, we will discuss in greater detail what a liver function test is, how it is conducted, and what the results imply. Furthermore, we will discuss who should be taking this test, underscoring the importance of early diagnosis.
What is a Liver Function Test?
Also known as a liver function panel test, the liver function test is a diagnostic method used to measure several substances produced by the liver. It helps locate the source of abnormalities by monitoring the levels of various proteins and enzymes in the blood:
- Alanine Transaminase (ALT): An elevated amount of ALT in the bloodstream may indicate considerable cellular necrosis and liver damage. This enzyme is mainly found in the liver, as well as the kidneys and skeletal muscles. It converts proteins into energy for the liver.
- Aspartate Transaminase (AST): An increased level of AST typically occurs after incidents of bruising, trauma, and infection. It is an enzyme that is found in parts of the body, such as the heart, brain, and pancreas, which metabolises amino acids. An AST test may be ordered by itself, but is often ordered as part of a group of liver function blood tests.
- Alkaline Phosphatase (ALP): This enzyme is measured, as an elevated amount of ALP may indicate intestinal or biliary damage. It helps to break down proteins and is present in the liver, bones, kidney tubules, lungs, and intestinal epithelium.
- Gamma-Glutamyl Transferase (GGT): It is an enzyme that functions like a transport molecule and plays an important role in helping the liver metabolise drugs and other toxins. It is mainly found in the liver but is also present in the gallbladder, spleen, and pancreas. Elevated levels of GGT could indicate liver damage.
- Bilirubin: The breakdown of haemoglobin in red blood cells results in a waste product known as bilirubin. It is measured to indicate the liver and bile tract function.
- Albumin: Albumin is the main protein produced by the liver. It plays several roles, such as transporting hormones and other substances throughout the body. It also helps to maintain osmotic pressure within the intravascular compartment. Abnormal levels of albumin could indicate liver damage or disease.
- Prothrombin Time (PT): Prothrombin is a precursor of thrombin, which is involved in blood coagulation. PT refers to the time it takes for blood to clot and is an indicator of the presence of liver cirrhosis or liver damage.
- Lactate Dehydrogenase (LDH): It is an enzyme that catalyses the conversion of pyruvate to lactate. LDH is present in all cells, but high amounts can be found in the liver, muscle, and kidney. If disease or injury damages tissues that have LDH, their cells release the enzyme into your bloodstream or other body fluids. Elevated amounts of LDH could indicate conditions such as hepatitis, shock, and hypoxia.
These tests alone cannot conclusively determine if there is an abnormality in the liver. Therefore, a gastroenterologist will typically conduct multiple tests to ensure you get a proper diagnosis. With this knowledge in mind, let’s understand what happens during a liver function test and how you can best prepare.
Preparing for a Liver Function Test: What to Expect
Like some other diagnostic blood tests, the liver function test will require you to fast for approximately 8-12 hours before the test. Apart from this, your doctor will advise you on other restrictions, like medications that could interfere with test results. It’s crucial that you tell your doctor the types of medications you take. After you have followed your doctor’s instructions, they will take a blood sample from your arm with a small needle.
It’s also important to know why you should get a liver function blood test done. The proceeding section of this article will delve into the risk factors and symptoms of an abnormal liver.
Why Do I Need a Liver Function Test?
Your gastroenterologist may recommend that you get a liver function test done if you exhibit any of the following symptoms of liver disease or damage:
- Nausea and vomiting
- Lack of appetite
- Fatigue
- Weakness
- Jaundice, a condition that causes your skin and eyes to turn yellow
- Swelling of the limbs and soft tissue
- Dark-colored urine and/or light-colored stool
Although you may not experience these symptoms, it is advisable that you get the test done if you are at high risk of liver disease. Liver diseases are common in those with:
- A family history of liver disease
- Hormonal disorders
- Heavy drinkers
- Obesity
- Type 2 Diabetes
- Frequent usage of certain medications that affect liver health
- Hepatitis B and C
If you exhibit any of these symptoms or are at risk of liver disease, please consult Alpha Digestive and Liver Centre’s gastroenterologist, Dr Benjamin Yip. With his clinical interests and years of experience in Gastroenterology, Hepatology, and Advanced Endoscopy, Dr Benjamin Yip is an experienced liver specialist in Singapore who can provide personalised and comprehensive treatment solutions to improve your liver health.
Book a consultation with us today to maintain a healthy liver.
References
- MedlinePlus. AST Test: MedlinePlus Lab Test Information. Medlineplus.gov. Published 2022. https://medlineplus.gov/lab-tests/ast-test/
- VA.gov | Veterans Affairs. Va.gov. Published 2014. https://www.hepatitis.va.gov/hcv/patient/diagnosis/labtests-prothrombin-time.asp
- MedlinePlus. Lactate Dehydrogenase (LDH) Test: MedlinePlus Lab Test Information. medlineplus.gov. Published 2020. https://medlineplus.gov/lab-tests/lactate-dehydrogenase-ldh-test/
- MedlinePlus. Liver Function Tests: MedlinePlus Lab Test Information. Medlineplus.gov. Published 2019. https://medlineplus.gov/lab-tests/liver-function-tests/
