I hope this isn't too broad or unanswerable a question but I'm wondering how many mL of blood serum are typically drawn out for a blood test for HIV. What's the minimum that's typically required?

1 Answer 1


HIV blood tests (for antigens and antibodies) are, at least where I practice, 4mL. However, if your doctor wants other blood tests she might add 1-2 vials of the same size. Depends on the organisation of the clinical lab and the tests draw.

I'm not fully familiar with how rapid HIV testing is done though. That might be slightly different.

  • 2
    If you already have the disease, they will likely draw at least 2 tests: 1 to test the viral load (HIV) and 1 to test the CD4 count (white blood cells), which may be 2 different vials. If it is screening, usually it is just one test. Do remember that you have about 5 Liters (5,000 mL) of blood in your body, as well as other fluid in your tissues, so 4 mL is a very small amount relatively.
    – DoctorWhom
    Feb 24, 2017 at 6:21
  • @DoctorWhom Would you mind turning that into an answer?
    – Narusan
    Nov 21, 2017 at 22:10