Diagnosis

HIV can be diagnosed through blood or saliva testing. Available tests include:

• Antigen/antibody tests. These tests usually involve drawing blood from a vein. Antigens are substances on the HIV virus itself and are usually detectable — a positive test — in the blood within a few weeks after exposure to HIV.

  Antibodies are produced by your immune system when it's exposed to HIV. It can take weeks to months for antibodies to become detectable. The combination antigen/antibody tests can take two to six weeks after exposure to become positive.

• Antibody tests. These tests look for antibodies to HIV in blood or saliva. Most rapid HIV tests, including self-tests done at home, are antibody tests. Antibody tests can take three to 12 weeks after you're exposed to become positive.
• Nucleic acid tests (NATs). These tests look for the actual virus in your blood (viral load). They also involve blood drawn from a vein. If you might have been exposed to HIV within the past few weeks, your doctor may recommend NAT. NAT will be the first test to become positive after exposure to HIV.

Talk to your doctor about which HIV test is right for you. If any of these tests are negative, you may still need a follow-up test weeks to months later to confirm the results.

Tests to stage disease and treatment

If you've been diagnosed with HIV, it's important to find a specialist trained in diagnosing and treating HIV to help you:

• Determine whether you need additional testing
• Determine which HIV antiretroviral therapy (ART) will be best for you
• Monitor your progress and work with you to manage your health

If you receive a diagnosis of HIV/AIDS, several tests can help your doctor determine the stage of your disease and the best treatment, including:

• CD4 T cell count. CD4 T cells are white blood cells that are specifically targeted and destroyed by HIV. Even if you have no symptoms, HIV infection progresses to AIDS when your CD4 T cell count dips below 200.
• Viral load (HIV RNA). This test measures the amount of virus in your blood. After starting HIV treatment the goal is to have an undetectable viral load. This significantly reduces your chances of opportunistic infection and other HIV-related complications.
• Drug resistance. Some strains of HIV are resistant to medications. This test helps your doctor determine if your specific form of the virus has resistance and guides treatment decisions.

Tests for complications

Your doctor might also order lab tests to check for other infections or complications, including:

• Tuberculosis
• Hepatitis B or hepatitis C virus infection
• STIs
• Liver or kidney damage
• Urinary tract infection
• Cervical and anal cancer
• Cytomegalovirus
• Toxoplasmosis