Liver Function Test (LFT)
Liver function tests (LFT) check how your liver is working. Your liver helps clean your blood, makes blood clotting factors, proteins, and enzymes, stores vitamins and minerals, and makes bile.
LFTs are a group of tests used to see how healthy your liver is, check for any causes of illness, and see how serious the illness is. LFTs are done by taking a sample of blood.
The range of values that are considered normal for most people will be given with your lab test results. You should be told how to get ready for the test. Some foods and medications can affect the results of the test.
Test done | What is it? | What does an abnormal value mean? |
ALT (Alanine Aminotransferase) | An enzyme released into the blood when the liver is harmed. | A low level is normal. A high value can be caused by harm to the liver such as hepatitis, cirrhosis, or a tumor in the liver. |
AST (Aspartate Aminotransferase) | An enzyme released into the blood when the liver is harmed. | A low level is normal. A high value can be caused by harm to the liver such as hepatitis, cirrhosis, or a tumor in the liver. |
ALP (Alkaline Phosphatase) | An enzyme found in tissues of the liver, bone, kidney, and intestine. | A low level of ALP can be caused by a low level of zinc, malnutrition, and temporarily after a blood transfusion or heart bypass surgery. A high value can be caused by liver disease, bone disease, Hodgkin’s lymphoma, congestive heart failure, ulcerative colitis, and bacterial infections. |
| Albumin | A protein made by the liver. It moves molecules in the blood and keeps fluid in the blood. It keeps fluid from leaking into the tissues. | A low value (hypoalbuminemia) can be caused by acute liver disease, nephrotic syndrome, infection, inflammation, malnutrition, malabsorption, cancer, diabetes, and hypothyroidism. A high value (hyperalbuminemia) can be caused by dehydration. |
| Total Protein | A measure of all proteins. Proteins are the building blocks of all cells. | A low value (hypoproteinemia) can be caused by malfunction of the kidneys or liver, malnutrition, and malabsorption. A high value (hyperproteinemia) can be caused by chronic inflammation, infections, and bone marrow disorders. |
| Bilirubin | A pigment that is a waste product of the breakdown of red blood cells. Buildup causes yellowing of the skin and eyes. | A low level is normal. A high value can be caused by anemia, cirrhosis of the liver, hepatitis, reaction to a medication, cancer, and gallstones. |
GGT (Gamma-glutamyl transferase) | An enzyme found in the kidney, liver, gallbladder, spleen, and pancreas. | A low level is normal. A high value can be caused by damage to ducts within the liver. This test helps figure out the cause of high ALP values. |
LDH (Lactate Dehydrogenase) | An enzyme involved in the making of energy in almost all cells of the body. | A low level is normal. A high value can be caused by the destruction of cells, anemia, infection, sepsis, kidney and liver disease, pancreatitis, testicular cancer, lymphoma, and progression of cancer. |
PT/INR (Prothrombin Time/International Normalized Ratio) | Measurement of amount of time it takes for a clot to form. | A prolonged PT/INR result means that it is taking longer than normal for the blood to clot which can be caused by liver disease, vitamin K deficiency, or coagulation factor deficiency. |
Note that liver disease from drinking too much alcohol or a viral infection can cause LFT results that are out of the normal range. Your health care team will help you understand the results of these tests.