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What is Hepatitis A test?

Hepatitis A test is used to detect the presence of hepatitis A virus (HAV) in the body by identifying the proteins secreted by the body’s immune system to fight against the virus.

Hepatitis A is a liver disease caused by HAV infection. It commonly affects children, and those below 6 years of age usually do not show any symptoms or are asymptomatic. The disease spreads through ingestion of food contaminated with the stool of an infected person and leads to liver inflammation. Though this inflammation is usually of acute form and subsides itself within 2 months without complications, early diagnosis and treatment are important to prevent the infection from spreading to healthy individuals.

The virus is not shed in stools once the person recovers from acute illness and the disease never develops a chronic stage. 

  1. Why is Hepatitis A test performed?
  2. How do you prepare for Hepatitis A test?
  3. How is Hepatitis A test performed?
  4. What do Hepatitis A test results mean?

Hepatitis A test is advised when the following symptoms are observed:    

No special preparation is required before going for hepatitis A test. Fasting before the test is not necessary.
However, it is important that you do not undergo any test that involves the use of the radioactive substance for 1 week before the hepatitis A test as it may lead to false-positive results.

About 7 mL of blood sample will be collected from your arm for this test. A lab technician will first swab the concerned area with alcohol and then insert a needle into your vein to withdraw blood sample into a vial.
Generally, there are no side effects associated with hepatitis A test. However, some people may experience the following     :

  • Headache or dizziness
  • Accumulation of blood under the skin
  • Excess flow of blood from the site of blood collection
  • Infection in rare cases

Your immune system secretes IgM and IgG antibodies (proteins) in response to the antigen released by HAV. HAV test measures the amount of these antibodies to help diagnose hepatitis A infection. Reverse transcriptase-polymerase chain reaction (RT-PCR) is a special test used to detect the genetic material (RNA) of HAV in a stool or blood sample.

Normal results:
Normal hepatitis A test results show negative IgM and IgG, which indicates the absence of HAV in the body.

Abnormal results:
Abnormal results can be interpreted as follows:

  • Positive IgM or anti-HAV IgM indicates an acute hepatitis A infection    
  • IgM antibodies appear in the blood 2 to 4 weeks after the infection and are detectable up to 8 weeks    
  • Positive IgG or anti-HAV IgG indicates chronic infection or previous infection. It may also appear if the person has received HAV vaccine    
  • IgG antibodies provide protection (life-long immunity) against HAV.
  • HAV RNA detected on the RT-PCR test confirms the presence of HAV infection.

Liver function tests (LFTs) are sometimes advised along with serology tests to measure substances or enzymes that are secreted by the liver during inflammation due to a viral infection.

  • High levels of aspartate aminotransferase and alanine transaminase in the blood indicate acute inflammation of the liver.

LFTs do not distinguish between different types of viral infections (hepatitis A, B, C, D, E, etc.); whereas, the serology test helps in differentiating between different types of infections on the basis of specific antibodies that are secreted by the body against the antigen of a specific type of virus.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

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References

  1. World Health Organization [Internet]. Geneva (SUI): World Health Organization; Hepatitis A
  2. American Academy of Family Physicians [Internet]. Leawood (KS); Hepatitis A
  3. Denise. D. Wilson. McGraw-Hill Manual of Laboratory and Diagnostic Tests. 1st Edition; ISBN10: 0071481524
  4. University of California San Francisco [Internet]. San Francisco, CA: Department of medicine; Hepatitis Virus Test or Panel
  5. William Marshall, Marta Lapsley, Andrew Day, Ruth Ayling. Clinical Biochemistry:Metabolic and Clinical Aspects. 3rd Edition: ISBN: 9780702054785.
  6. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Positive Test Results for Acute Hepatitis A Virus Infection Among Persons With No Recent History of Acute Hepatitis