Blood tests help determine whether the liver is functioning normally.
Your liver is located in the upper right side of your abdomen. It performs many necessary functions, including detoxifying harmful substances and producing blood-clotting proteins and bile. Many diseases and conditions can damage your liver, including infections and drinking too much alcohol. Over time, a damaged liver can become so severely scarred that it no longer functions normally, a condition known as cirrhosis. Blood tests help determine whether liver damage has occurred and how well the liver is functioning. However, other tests are needed to confirm a diagnosis of cirrhosis.
A liver panel is a group of blood tests that detects problems with liver function, but cannot diagnose a particular disease or condition. Although the specific tests included in a liver panel vary from one laboratory to another, common tests include bilirubin, ALT, AST, ALP, albumin and prothrombin time. The bilirubin test measures the level of waste products from red blood cell breakdown. A person with cirrhosis may have a normal or elevated bilirubin level, depending on the underlying cause of the condition and overall function of the liver.
Liver enzymes are proteins that promote chemical changes. Enzymes such as alanine aminotransferase (ALT), alkaline phosphatase (ALP) aspartate aminotransferase (AST) are released into the bloodstream when the liver is damaged. High liver enzyme levels are common with some forms of cirrhosis.
Serum albumin concentration, a measure of this protein in the blood, is often lower than normal when the liver is not functioning properly. A prothrombin time test, also known as a PT/INR, measures how quickly blood clots form. Prothrombin time increases when cirrhosis impairs the liver's ability to make clotting factors.
Complete Blood Count
A complete blood count test, also called a CBC, is often ordered along with a liver panel for people with suspected liver damage or cirrhosis. Although a CBC does not measure liver function or cirrhosis, the test can provide clues about what may be occurring in the body that could adversely affect the liver. A CBC includes counts of the white blood cells, red blood cells and platelets.
White blood cells defend the body against infections, so high levels may indicate infection or inflammation. The red blood cells transport oxygen in the body, and platelets are cell fragments needed for blood clotting. A low platelet count, a condition called thrombocytopenia, is common among people with cirrhosis of the liver. However, a low platelet count can occur with other conditions, including HIV infection, mononucleosis, Rocky Mountain spotted fever and leukemia. Radiation therapy, chemotherapy and certain medications can also cause a low platelet count.
To determine the cause of liver damage, doctors may order blood tests for hepatitis B and hepatitis C, viral infections of the liver. A blood hyaluronic acid level may be ordered to help assess the amount of scarring in the liver. Other blood tests can be ordered to determine if liver damage is due to a genetic disorder, cancer or an autoimmune disorder, such as primary biliary cirrhosis.
Doctors use a calculation called the MELD score to assess the severity of liver failure, usually caused by cirrhosis. The MELD score is calculated from the results of 3 blood tests: PT/INR, bilirubin and creatinine, which is a measure of kidney function. MELD scores range from 6 to 40, with higher scores indicating more serious illness. MELD scores correlate with short-term prognosis and are used to assess a patient's need for a liver transplant.