LIVER FUNCTION TESTS
LFTs (liver function tests) are a group of blood tests that can help to show how well a person’s liver is working. LFTs include measurements of albumin, various liver enzymes (ALT, AST, GGT and ALP), bilirubin, prothrombin time, cholesterol and total protein. All of these tests can be performed at the same time with a simple blood test.
Why Get Tested? To screen for, detect, evaluate, and monitor for liver inflammation and damage.
When to Get Tested? Periodically to evaluate liver function; whenever you are at risk for liver injury; when you have a liver disease; when you have symptoms such as jaundice
What is Required? A blood sample drawn from a vein in your arm
Test Preparation Needed? None
Albumin (ALB) Albumin is a protein made by the liver. It is used in a number of scenarios to help diagnose disease, to monitor changes in health status with treatment, or with disease progression. It can be used to evaluate liver function, in conjunction with a creatinine or BUN test to evaluate kidney function, or along with prealbumin to evaluate a person’s nutritional status.
- Normal values: 4 – 6
- Elevated: Usually indicates dehydration
- Below normal: Can indicate liver disease, insufficient protein intake, and can be sen in inflammation, shock, malnutrition. and with conditions where the body does not properly absorb protein (Chrohn’s disease, celiac disease).
- Drugs that may increase albumin: anabolic steroids, androgens, growth hormones, insulin
*** If someone is receiving large amounts of intravenous (IV) fluids, the results may be inaccurate.
Alkaline Phosphatase (ALK PHOS or ALP) Alkaline phosphatase is an enzyme found in many organs in the body, including the liver. In conditions that affect the liver, damaged liver cells release increased amounts of ALP into the blood.
This test is evaluated with other liver function tests. With some forms of liver disease, such as hepatitis, ALP is usually much less elevated than AST and ALT. This test is also used to detect blocked bile ducts.
- Normal values: 30 – 120
- Elevated: A warning sign that there is some type of liver dysfunction resulting in liver tissue damage.
- Below normal: Usually not significant.
- Drugs that may increase ALP: anti-epileptics
- Drugs that may lower ALP: oral contraceptives
Alanine Aminotransferase (ALT or SGPT) This protein is found primarily in the liver. The test is used to detect liver injury and iss ordered in conjunction with AST to for and/or help diagnose liver disease. AST and ALT are considered to be two of the most important tests to detect liver injury. Sometimes the AST is compared directly to ALT and AST/ALT ratio is calculated. The ratio may then be used to distinguish between different causes of liver damage.
Very high levels of ALT (more than 10 times the highest normal level) are usually due to acute hepatitis. In acute hepatitis, ALT levels usually stay high for 1-2 months but can take much longer to return to normal. ALT levels may also be greatly elevated by exposure to drugs or other substances that are toxic to the liver as well as conditions that cause decreased blood flow to the liver.
ALT levels are not usually as high in chronic hepatitis, and are often less than 4 times normal range. Other causes of moderate increases in ALT include obstruction of bile ducts, cirrhosis, and tumors in the liver. In most types of liver disease, the ALT level is higher than the AST, and the AST/ALT ratio will be low.
Drugs that may cause increased levels include alcohol, barbiturates, narcotics, and diuretics.
Increased levels may also be seen with: Gi bleeding, muscular exertion, and tourniquet use Drugs that may decrease levels include broad-spectrum antibiotics, levodopa, lactobacillus, and potassium salts.
Aspartate Aminotransferase (AST or SGOT) This protein is found primarily in the liver. It is released into the blood when there has been some sort of liver tissue damage.
- Normal values: less than 35
- Elevated: Indicates tissue damage as a result of such things as obstruction, hepatitis, or cirrhosis.
- Below normal: Usually not significant
- Drugs that may increase: shot or injection into the muscle tissue and even strenuous exercise
Total Bilirubin (TBIL) Bilirubin is a normal component of red blood cells. When these cells break down free bilirubin is released in the blood. Bilirubin is then carried to the liver where it is broken down and excreted. When the liver is not functioning properly, bilirubin builds up in the body, causing jaundice (yellowing of the skin and eyes and darkening of the urine).
- Normal values: less than 1.0
- Elevated: usually caused by a dysfunction of the system that breaks down bilirubin which includes the liver. Such an elevation can be caused by an obstruction or liver failure.
- Drugs that may cause increased blood levels of total bilirubin include anabolic steroids, antibiotics, antimalarials, ascorbic acid, Diabinese, codeine, diuretics, epinephrine, oral contraceptives, and vitamin A.
5’N’Tase Higher levels of the enzyme 5’N’Tase (5’nucleotidase), also known as 5’NT, in your blood indicate a problem with bile secretion. Hepatitis or cirrhosis can cause a blockage of bile flow.
GGT refers to gamma-glutamyl transferase, but it’s also called gamma-glutamyl transpeptidase (GGTP) or Gamma-GT. High levels of GGT are found in the liver, bile ducts, and the kidney. Bloodstream GGT levels will be higher in people with diseases of the liver and bile ducts. GGT: males 2-30 U/L; females 1-24 U/L.
Drugs that may cause increased GGT levels include alcohol, phenytoin, and phenobarbital.
Drugs that may cause decreased levels include oral contraceptives.
PT (prothrombin time) test measures how quickly your blood clots, which is dependent on clotting factors (proteins) that are made by the liver. The PT test is used as a marker of advanced liver disease and can indicate blood-clotting problems where it takes you longer to stop bleeding. Your laboratory may also give PT results that have been converted to an internationally recognized and easily comparable value that’s called the International Normalized Ratio (INR). The INR is one of the three factors used to determine wait time for a liver transplant.