Medical Terminology: Liver Tests

1. What are Liver Tests?
The liver is the largest gland in the body that produces and secretes substances. The liver synthesizes albumin, which maintains blood volume and clotting factors. The liver also synthesizes, stores, and metabolizes fatty acids and cholesterol. Fatty acids are used for energy by the body. The liver stores and metabolizes carbohydrates. Carbohydrates are converted into glucose for energy.
The liver forms and secretes bile. Bile contains acids that help the intestines absorb fats and vitamins A, D, E, and K, which are fat-soluble vitamins. In addition, the liver clears the body of medications and harmful chemicals such as bilirubin, which is the result of the metabolism of aged red blood cells, and ammonia, which is the result of metabolism of proteins. The liver transforms these chemicals into components that are easily excreted by the body in urine or stool.

2. Hepatitis A Virus (HAV) Test
The hepatitis A virus (HAV) test is performed to screen for hepatitis A virus infection and the effectiveness of the hepatitis A vaccine.

Understanding the Hepatitis A Virus Test
A patient who is or has been infected with the hepatitis A virus (HAV) will have hepatitis A antibodies in his or her blood. A patient who received the hepatitis A vaccine will also have these antibodies, indicating the effectiveness of the vaccine. If not recently immunized, these antibodies indicate pathology versus adequate titers from being immunized. There are two types of antibodies:
- IgM anti-HAV: The presence of this antibody indicates that the patient was recently infected. This antibody is detectable 2. weeks after being infected and remains in the blood for 3. to 12. months.
- IgG anti-HAV: The presence of this antibody indicates that the patient has been infected at some point. This antibody is detectable 8. to 12. weeks following the infection and remains in the blood.

3. Hepatitis B Virus (HBV) Test
Hepatitis B virus (HBV) tests are performed to screen for hepatitis B virus infection and the effectiveness of the hepatitis B vaccine and treatment for a hepatitis B virus infection. These tests are also used to assess if blood designated for transfusion is infected with the hepatitis B virus.

Understanding the Hepatitis B Virus Tests
Hepatitis B is a virus that can cause an infection. There are several hepatitis B virus tests used to determine if blood has signs of HBV. There are three signs:
- HBV antibodies: HBV antibodies are produced as part of the immune response to the presence of HBV in the patient and may remain in the patient’s blood long after HBV is destroyed.
- HBV antigens: HBV antigens are markers created by HBV when HBV infects the patient.
- HBV DNA: HBV DNA is present when HBV infects the patient.
There are seven types of HBV tests:
. Hepatitis B Surface Antigen (HBsAg): This is the first test that detects HBV antigen even before symptoms are present. It is also used to detect if the patient will be an HBV carrier if the HBsAg level is elevated >6. months.
. Hepatitis B Surface Antibody (HBsAb): This test detects HBV antibodies, which are elevated 4. weeks after HBsAg is no longer detectable. The test is used to determine if the patient requires an HBV vaccination.
. Hepatitis B e-Antigen (HBeAg): This test detects the HBeAg antigen that is present if the patient is currently infected and is used to monitor HBV treatment.
. Hepatitis DNA Test: This test determines the level of HBV DNA in the patient’s blood and is used to monitor treatment for chronic HBV infection.
. Hepatitis B Core Antibody (HBcAb): This test detects the HBcAb antibody a month after the HBV infection and is used to screen transfused blood for hepatitis B.
. Hepatitis B Core Antibody IgM (HBcAbIgM): This test detects the HBcAbIgM antibody within 6. months of the patient becoming infected with HBV.
. Hepatitis B e-Antibody (HBeAb): This test detects the HBeAb antibody, indicating that the patient has almost recovered from an acute HBV infection.

4. Alanine Aminotransferase (ALT) Test
The alanine aminotransferase (ALT) test is performed to screen for liver disorder and assess the underlying cause of jaundice. This test is also administered to assess for side effects of medications that can cause liver damage.

Understanding the Alanine Aminotransferase Test
Alanine aminotransferase, formerly called serum glutamic pyruvic transaminase (SGPT), is an enzyme mainly found in the liver, but is also in the heart, pancreas, muscles, and kidneys in small amounts. Damage to the liver caused by injury or disease results in the release of ALT in the blood. The ALT test measures the level of ALT in the blood as a way to detect liver disease.

5. Alkaline Phosphatase (ALP) Test
The alkaline phosphatase (ALP) test is used to screen for liver disorder and to assess the side effects of medications that can cause liver damage. This test is also used to screen for rickets, osteomalacia, Paget’s disease and bone tumor, along with assessing the effectiveness of treatment of these diseases. It is also administered to assess the underlying cause of high calcium level in blood.

Understanding the Alkaline Phosphatase Test
Alkaline phosphatase is an enzyme produced mainly in the liver and is also produced by bones, kidneys, intestines, and placenta. The ALP test measures the level of ALP in blood.
An alkaline phosphatase isoenzymes test is likely to be ordered if the ALP level is high. The health care provider may order an ultrasound or CT scan. The gamma glutamyl transferase (GGT), 5-nucleotidase, or the gamma glutamyl transpeptidase (GGTP) test might be ordered if the ALP level is high to differentiate between bone ALP and liver ALP.

6. Ammonia Test
The ammonia test is performed to screen for liver disorder and assess the treatment of liver disease. It is also administered to screen for Reye’s syndrome, hyperalimentation, cirrhosis, and acute liver failure.

Understanding the Amonia Test
Ammonia is formed when bacteria in the intestines break down protein. Ammonia is then converted into urea by the liver, which is excreted by the kidney in urine. The ammonia test measures the ammonia level in the blood. If the liver is unable to convert ammonia to urea, ammonia levels in blood increase, indicating that there may be a liver function problem.

7. Aspartate Aminotransferase (AST) test
The aspartate aminotransferase (AST) test is used to screen for liver disorder, hepatitis, and cirrhosis. It is also administered to assess treatment of liver disease, side effects of medication that cause liver damage, and the underlying cause of jaundice.

Understanding the Aspartate Aminotransferase Test
Aspartate aminotransferase, previously known as serum glutamic oxaloacetic transaminase (SGOT), is an enzyme in the liver, heart, pancreas, kidneys, red blood cells, and muscle tissues. When these tissues or cells are damaged there is an increase of AST in the blood 6. to 10. hours after the damage that remains for 4. days. The AST test measures the level of AST in the blood.
The health care provider orders tests to measure AST and ALT in a normal screen for liver damage and liver disease. The AST test is more effective in detecting liver damage caused by alcohol abuse than the ALT test. As the patient recovers from tissue damage, the AST level in the blood decreases.

8. Bilirubin Test
The bilirubin test is used to screen for liver disorder, hepatitis, cirrhosis, blocked bile duct from gallstone or pancreatic tumor, hemolytic anemia, hemolytic disease, neonatal jaundice, and the side effect of medication that causes liver damage.

Understanding the Bilirubin Test
The liver breaks down old red blood cells into bilirubin, which becomes the brownish yellow component of bile. Bilirubin is excreted through feces. Bilirubin gives feces its brown color. Indirect (unconjugated) bilirubin, which is insoluble in water, is carried by the blood to the liver, where indirect bilirubin is transformed into direct bilirubin, which is soluble in water. The bilirubin test measures the total bilirubin level in the blood and the direct bilirubin level in the blood. Indirect bilirubin is measured by subtracting the direct bilirubin level from the total bilirubin level.

Basic Questions
Liver Tests

1. What does the liver synthesize, store, and metabolize?
The liver synthesizes, stores, and metabolizes fatty acids and cholesterol.

2. What does the liver form and secrete?
The liver forms and secretes bile.

3. How does the liver clear the body of medication and harmful chemicals?
The liver transforms these chemicals into components that are easily excreted by the body in urine or stool.

4. What is the purpose of the hepatitis A virus (HAV) test?
The HAV test is used to screen for hepatitis A virus infection and the effectiveness of the hepatitis A vaccine.

5. What is IgM anti-HAV?
The presence of the antibody IgM anti-HAV indicates that the patient was recently infected. This antibody is detectable 2. weeks after being infected and remains in the blood for 3. to 12. months.

6. What are hepatitis B virus (HBV) antigens?
HBV antigens are markers created by the HBV when HBV infects the patient.

7. What are HBV antibodies?
HBV antibodies are produced as part of the immune response to the presence of HBV in the patient and may remain in the patient’s blood long after HBV is destroyed.

8. What is the hepatitis B surface antigen (HBsAg) test?
HBsAg is the first test that detects HBV antigen even before symptoms are present. It is also used to detect if the patient will be an HBV carrier, if the HBsAg level is elevated >6. months.

9. What is the hepatitis B e-antigen (HBeAg) test?
HBeAg detects the HBeAg antigen, which is present if the patient is currently infected and is used to monitor HBV treatment.

10. What is the hepatitis B core antibody (HBcAb) test?
HBcAb detects the HBcAb antibody a month after the HBV infection and is used to screen transfused blood for hepatitis B.

11. What is the hepatitis B e-antibody (HBeAB) test?
The HBeAb test detects the HBeAb antibody, indicating that the patient has almost recovered from an acute HBV infection.

12. What is the purpose of the alanine aminotransferase (ALT)test?
The ALT test is used to screen for liver disorder and assess the underlying cause of jaundice. This test is also administered to assess the side effects of medications that can cause liver damage.

13. What is alanine aminotransferase?
Alanine aminotransferase, formerly called serum glutamic pyruvic transaminase (SGPT), is an enzyme mainly found in the liver; but it is also present in the heart, pancreas, muscles, and kidneys in small amounts.

14. Why is alanine aminotransferase measured in the blood?
Damage to the liver caused by injury or disease results in the release of ALT in the blood.

15. What is the purpose of the alkaline phosphatase (ALP) test?
The ALP test is used to screen for liver disorder and assess the side effects of medications that can cause liver damage. This test is also used to screen for rickets, osteomalacia, Paget’s disease, and bone tumor, along with assessing the effectiveness of treatment of these diseases. It is also administered to assess the underlying cause of high calcium levels in the blood.

16. Why is the ammonia test ordered?
The ammonia test is performed to screen for liver disorder and assess the treatment of liver disease. It is also administered to screen for Reye’s syndrome, hyperalimentation, cirrhosis, and acute liver failure.

17. How is ammonia formed?
Ammonia is formed when bacteria in the intestines break down protein.

18. What is the relationship between ammonia and the liver?
Ammonia is then converted into urea by the liver, which is excreted by the kidney in urine.

19. Why is ammonia measured in blood?
If the liver is unable to convert ammonia to urea, ammonia levels in blood increase, indicating that there may be a liver function problem.

20. What is aspartate aminotransferase (AST)?
AST, previously known as serum glutamic oxaloacetic transaminase (SGOT), is an enzyme in the liver, heart, pancreas, kidneys, red blood cells, and muscle tissues.

21. How long will AST remain in the blood?
When the liver, heart, pancreas, kidneys, red blood cells, and muscle tissues or cells are damaged, there is an increase of AST in the blood 6. to 10. hours after the damage and it remains for 4. days.

22. What is bilirubin?
The liver breaks down old red blood cells into bilirubin, which becomes the brownish yellow component of bile.

23. What is indirect bilirubin?
Indirect bilirubin is carried by the blood to the liver where indirect bilirubin is transformed into direct bilirubin.

24. What is the difference between direct and indirect bilirubin?
Indirect (unconjugated) bilirubin is insoluble in water. Direct bilirubin is soluble in water.

25. What is the relationship between feces and bilirubin?
Bilirubin gives feces its brown color.