Understanding HIV-Related Lab Tests

1. Understanding HIV-Related Lab Tests Jordan E. Lake, MD, MSc AAHU August 27, 2014

2. Labs 101 “Why do you need to take so much blood!?!”

3. Labs 101: Three Questions • What labs do we draw? • What do these labs tell us? • How often do we need these labs?

4. T cells 101 • T cell: a type of immune system cell • T cells become infected by HIV when the virus recognizes proteins on the T cell surface • One of these proteins is called CD4 • Doctors and patients may talk about T cells or CD4 cells (same thing)

5. T cells 101 • The number of T cells tells us how healthy the immune system is (normal ≥700 cells/mm3) • As the immune system becomes weaker from HIV, the number of T cells goes down (they die and your body can’t make more)

6. T cells 101 • When T cells are not infected with HIV, they help to fight infection and cancer • As T cell number decreases and T cells become weaker, their ability to “help” goes down

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8. T cells 101 What does the number of T cells tell me? • <200cells/mm3: AIDS, immune system very weak • 200-349cells/mm3: immune system still weak, some infections more common • 350-499cells/mm3: immune system is getting stronger • ≥500cells/mm3: Ideal

9. HIV Viral Load 101 • Viral load (VL) is the amount of HIV in the blood in copies/mL • Without HIV medicines, VL is high • With effective HIV medicines, no new HIV viruses are made, and the VL goes down

11. HIV Viral Load 101 Q: What does “undetectable” mean? A: Undetectable means there is less HIV in the blood than the test can detect, NOT that the virus is gone from the body -The virus lives in many places in the body other than your blood -Cells in the blood can be infected with HIV but not release virus into the blood

12. Where is the HIV Virus in the Body?

13. How Do HIV Medications Affect T cells and the HIV Viral Load?

14. Effective HIV Medicines • Stops new HIV virus from being made • Stops T cells from dying • Allows the body the chance to make new T cells

15. atripla.com

17. HIV Genotype 101 • The genotype tells us what medications the HIV virus is sensitive to • It is specific to each person, and helps doctors choose medication regimens • Also called a “resistance test”

18. HIV Genotype 101

19. When To Check Labs • T cell count: at diagnosis, then every 3-6 months • HIV Viral Load: at diagnosis, 4 weeks after starting HIV medicines, 12 weeks after starting medicines, then 2-3 times per year • Genotype: at diagnosis, if VL going up on medicines and resistance suspected

20. Other Labs We Check • Kidneys: blood creatinine, urinalysis • Liver: AST, ALT, bilirubin • Anemia: hemoglobin • Immune system: white and red blood cell counts and characteristics • Cholesterol: lipid panel • STIs: RPR, Gonorrhea/Chlamydia as appropriate for individual patient • Viral hepatitis: Hepatitis A,B, and C at diagnosis, Hepatitis B and C if liver abnormalities, plus Hepatitis C antibody yearly for MSM