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Liver Function Blood Tests

Last updated Oct. 11, 2015


What are the other Names for this Test? (Equivalent Terms)

  • Hepatic Function Panel Blood Tests
  • LFTs
  • Liver Function Tests

What is Liver Function Blood Test? (Background Information)

  • The liver is a large organ located in the right side of the mid-back. It produces enzymes, clotting factors, and bile; detoxifies the body of harmful compounds; stores vitamins and minerals; and stores and metabolizes glycogen for energy
  • Because of its intimate connection with so many different bodily processes, the liver is subject to damage from several fronts. Alcohol and pharmaceutical drugs may cause liver damage, as may infections and bile duct obstructions
  • Liver damage may cause a variety of symptoms. Jaundice, a yellowing of the eyes and skin, is a common symptom. It is caused by the inability of the liver to help in the excretion of bilirubin
  • Bilirubin is a byproduct released after red blood cells are recycled in the spleen. It is insoluble in blood, so it is transported to the liver to be converted into a form that is soluble, in order that it may be excreted through urine
  • If the liver is damaged, it is unable to process bilirubin. Consequently, bilirubin accumulates in blood to cause yellow discoloration of the skin and whites of the eyes
  • The liver normally converts bilirubin, a brownish-yellow substance, into urobilinogen, which is a clear substance. However, if the liver is damaged or the biliary duct is obstructed, the liver’s ability to make this conversion is impaired. As a result, bilirubin may leak into the urine and make it a dark amber color

The Liver Function Blood Tests help assess liver functioning by measuring the levels of various substances produced by the liver. These include:

  • Alanine aminotransferase (ALT): An enzyme found mostly in liver cells; its presence in blood in significant amounts indicates hepatitis
  • Alkaline phosphatase (ALP): An enzyme whose presence in blood often indicates bile duct obstruction
  • Aspartame aminotransferase (AST): An enzyme whose presence in blood in significant amounts indicates liver damage
  • Bilirubin is measured as total bilirubin and conjugated bilirubin, which is a form of bilirubin that has been modified in the liver
  • Albumin: One of the most abundant carrier proteins in blood; it is the main protein produced by the liver and is associated with liver health
  • Total protein: Measures all proteins found in blood, including albumin and antibodies (the body’s defense proteins)
  • Gamma-glutamyl transferase (GGT): An enzyme found mostly in the liver cells
  • Lactate dehydrogenase (LDH): An enzyme found inside many cell types whose presence in blood in significant quantities indicates tissue damage
  • Prothrombin time (PT): It helps in measuring the time it takes to form a blood clot. This is indicative of liver health because the liver helps in producing the clotting proteins

What are the Clinical Indications for performing the Liver Function Blood Test?

Following are the clinical indications for performing the Liver Function Blood Tests:

  • Monitoring liver health during drug therapies that are potentially damaging to the liver
  • Family history of liver disease
  • Alcoholism
  • Fatigue
  • Weight loss
  • Loss of appetite
  • Nausea
  • Vomiting
  • Abdominal swelling and/or pain
  • Yellowing of the skin and whites of the eyes (jaundice)
  • Dark, amber-colored urine
  • Itching

How is the Specimen Collected for Liver Function Blood Test?

Following is the specimen collection process for Liver Function Blood Tests:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected, by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Liver Function Blood Test Result?

The significance of the Liver Function Blood Test result is explained:

The following may indicate acute liver disease:

  • Normal or increased bilirubin
  • Increased ALT
  • Increased AST
  • Normal or increased ALP
  • Normal albumin
  • Normal PT 

The following may indicate chronic liver disease:

  • Normal or increased bilirubin
  • Increased ALT
  • Increased AST
  • Normal or increased ALP
  • Normal albumin
  • Normal PT 

The following may indicate alcoholic liver inflammation (hepatitis):

  • Normal or increased bilirubin
  • Increased ALT
  • Increased AST
  • Normal or increased ALP
  • Normal albumin
  • Normal PT 

The following may indicate cirrhosis:

  • Normal or increased bilirubin
  • Increased ALT
  • Increased AST
  • Normal or increased ALP
  • Normal or decreased albumin
  • Prolonged PT 

The following may indicate bile duct obstruction:

  • Normal or increased bilirubin
  • Normal or increased ALT
  • Normal or increased AST
  • Increased ALP
  • Normal or decreased albumin
  • Normal PT 

The following may indicate cancer that has spread to the liver:

  • Normal bilirubin
  • Normal or decreased ALT
  • Normal or decreased AST
  • Increased ALP
  • Normal albumin
  • Normal PT 

The following may indicate cancer that has originated in the liver (hepatocellular carcinoma or HCC):

  • Normal or increased bilirubin
  • Increased ALT
  • Increased AST
  • Normal or increased ALP
  • Normal or decreased albumin
  • Prolonged PT 

The following may indicate autoimmune liver disease:

  • Normal or increased bilirubin
  • Increased ALT
  • Increased AST
  • Normal or increased ALP
  • Decreased albumin
  • Normal PT

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Follow-up exams may be performed to gain a better picture of liver health. These exams include hepatitis virus testing, liver biopsy, and imaging scans

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

What are some Useful Resources for Additional Information?

Please visit our Laboratory Procedures Center for more physician-approved health information:

http://www.dovemed.com/common-procedures/procedures-laboratory/ 

References and Information Sources used for the Article:

Lab Tests Online (2014, June 4). Retrieved May 15, 2015 from http://labtestsonline.org/understanding/analytes/liver-panel/

Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.

Schnell, Z. B., Van, L. A., & Kranpitz, T. R. (2003). Davis's Comprehensive handbook of laboratory and diagnostic tests: With nursing implications. Philadelphia: F.A. Davis. 

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 15, 2015
Last updated: Oct. 11, 2015