Liver Function Test (LFT)

The Liver Function Test (LFT or Hepatic Function Test) is a blood test panel that includes several tests that measure specific proteins and liver enzymes to get an overall sense of how well the liver is working.

The liver filters the blood coming from the digestive tract, before passing it along to the rest of the body. This organ also detoxifies chemicals and metabolizes drugs and secretes bile that ends up back in the intestines. The liver also makes proteins that are important for blood clotting and other functions.

What is the Liver and Where is it Located?

The Liver is a key component in the human digestive system. It typically weighs over three pounds, and it’s usually about the size of a football. It’s located on the upper right side of the abdomen behind the ribs and underneath the diaphragm.

What Does the Liver Do?

The liver carries out over 500 tasks throughout the body, but its main focus is metabolic. The human liver filters up to 1.5 liters of blood per minute. At any given time the liver holds 10% of the total blood in your body. Anything consumed goes through the liver, which then breaks down the food, extracts the energy, and removes any toxins from the bloodstream.

Additionally, the liver is constantly monitoring and regulating the amount of sugar in the bloodstream. It keeps such a close watch on the bloodstream by receiving blood from the digestive organ through a vein referred to as “the portal vein.” Once the portal vein delivers the blood and the liver filters out the toxins, it will store vitamins and minerals then release them into the bloodstream as needed.

The Liver is full of many little cells which are called “hepatocytes.” These cells act as sorting centers to determine what to put back in the bloodstream, what nutrients to process, what to store, and what should be eliminated from the body via stool.

Up to 1,000 milliliters of bile are produced by the liver each day. Bile is a yellow or green liquid that is transported from the liver to the small intestine, where it is used to aid in the break down and storage of fat.

What is the Liver Function Test?

The Liver Function Test checks for the following:

• Alanine aminotransferase (ALT/SGPT) – ALT is an enzyme found predominantly in the cells of the liver. When the liver is damaged, ALT is released into the blood.
• Albumin – Albumin is a protein made by the liver. Measuring levels of albumin is helpful in diagnosing liver disease. An albumin test measures how well your liver is making the proteins that your body needs.
• Albumin/Globulin Ratio (calculated) – The A/G ratio is calculated from measured total protein, measured albumin, and calculated globulin (total protein – albumin) to help diagnose diseases.
• Alkaline phosphatase (ALP) – In conditions affecting the liver, damaged liver cells release increased amounts of ALP into the blood.
• Aspartate aminotransferase (AST/SGOT) – AST is a liver enzyme that is useful in helping to diagnose liver diseases.
• Bilirubin, Total – This test measure direct and indirect levels of bilirubin for a total bilirubin value. In cases of an obstruction or inflamed liver, the liver cannot eliminate excess bilirubin. When the body has too much bilirubin, your skin and the whites of your eyes will start to yellow causing a condition called jaundice.
• Bilirubin, Direct – Bilirubin is made in the body when old red blood cells are broken down. Bilirubin attached to sugar is called “direct” or “conjugated” bilirubin.
• Bilirubin, Indirect – Bilirubin that is not attached to sugar is called “indirect” or “unconjugated” bilirubin.
• Globulin (calculated) – Globulin is a protein made in your liver and helps the immune system fight infections. Low globulin levels can be a sign of liver damage or other conditions.
• Total Protein – Total protein measurements can help diagnose liver diseases. Total Protein measures the amount of protein in your blood. The two main proteins found in the blood are globulins and albumin.

How Do You Know if Your Liver is Failing?

You should test your liver function if you experience any of the following symptoms:

• Yellow looking skin or eyes (jaundice)
• Abdominal pain
• Itchy skin
• Dark-colored urine
• Light stool color
• Chronic fatigue
• Nausea or vomiting
• Loss of hunger
• Easily bruised skin

Please note that liver conditions can sometimes have no symptoms. It is important to learn what risks can cause liver disease, and if any apply to you, get tested.

Who Should Take The LFT Test?

It is recommended that the following groups of people are at risk of liver disease and should get their liver function tested:

• Women between the ages of 35 and 60 Men between the ages of 30 and 40
• If your family has a history of liver disease
• If you had a blood transfusion before the year 1992
• Obesity
• Diabetes
• Exposure to chemicals
• Heavy drinking
• Unprotected sex
• Direct exposure to human blood or bodily fluids
• Tattoos or body piercings

How is a Liver Function Test Administered?

It is important to note that fasting is not required to take this test. A small amount of blood will be drawn, and your blood will be tested for a combination of different chemicals.