Why hbsag test done

You don't need to do anything special to prepare for this test. Talk to your doctor if you have any concerns about the need for the test, its risks, or how it will be done. To help you understand the importance of this test, fill out the medical test information form. The health professional taking a sample of your blood will:. The blood sample is taken from a vein in your arm.

An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch. There is very little chance of a problem from having a blood sample taken. More tests may be needed to see if you have an acute or chronic infection. Your doctor will talk with you about anything that might keep you from having the test or that may change the test results.

Current as of: September 23, Thomas London MD - Hepatology. Author: Healthwise Staff. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use and Privacy Policy. Learn how we develop our content. To learn more about Healthwise, visit Healthwise. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

Top of the page. Test Overview Hepatitis B tests are blood tests that show whether you have an active hepatitis B infection. The tests look for different signs of infection: Antigens , which are made by bacteria or viruses. Antibodies , which are made by the body to fight infection. Hepatitis B DNA , which is the virus's genetic material. Most common tests The most common tests are: Hepatitis B surface antigen.

This antigen is the earliest sign of an active hepatitis B infection. It may be present before symptoms occur.

You can also infect others. Your healthcare provider may give you medicines if you don't recover after 6 months. The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. Having a blood test with a needle carries some risks.

These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. You don't need to prepare for this test.

Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use. Search Encyclopedia. Hepatitis B Surface Antigen Does this test have other names? HBsAg What is this test? Why do I need this test? The most common symptom is extreme tiredness. A positive result means you have hepatitis B and can spread the virus.

This test is used together with other hepatitis B tests to determine the state of a hepatitis B infection. Positive results usually mean you have acute or chronic hepatitis B.

A hepatitis B surface antibody test is used to check for immunity to HBV. A positive test means you are immune to hepatitis B. There are two possible reasons for a positive test. You may have been vaccinated, or you may have recovered from an acute HBV infection and are no longer contagious. Liver function tests are important in individuals with hepatitis B or any liver disease. Liver function tests check your blood for the amount of enzymes made by your liver. High levels of liver enzymes indicate a damaged or inflamed liver.

These results can also help determine which part of your liver may be functioning abnormally. If these tests are positive, you might require testing for hepatitis B, C, or other liver infections. Hepatitis B and C viruses are a major cause of liver damage throughout the world. You will likely also require an ultrasound of the liver or other imaging tests. Talk to your doctor immediately if you think you have been exposed to hepatitis B within the last 24 hours.

If you have not been vaccinated, it may be possible to prevent infection by receiving the hepatitis B vaccine and an injection of HBV immune globulin. This is a solution of antibodies that work against HBV. Most people will overcome an acute infection on their own. However, rest and hydration will help you recover. To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you.

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You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail. Your in-depth digestive health guide will be in your inbox shortly. You will also receive emails from Mayo Clinic on the latest health news, research, and care. If you've been diagnosed with hepatitis B infection, the following suggestions might help you cope:.

You're likely to start by seeing your family doctor or a general practitioner. However, in some cases, you may be referred immediately to a specialist.

Doctors who specialize in treating hepatitis B include:. Listing questions for your doctor can help you make the most of your time together. For hepatitis B infection, some basic questions to ask your doctor include:. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version. This content does not have an Arabic version. Diagnosis Your doctor will examine you and look for signs of liver damage, such as yellowing skin or belly pain.

Tests that can help diagnose hepatitis B or its complications are: Blood tests. Blood tests can detect signs of the hepatitis B virus in your body and tell your doctor whether it's acute or chronic.