How much blood do they take in a blood test?
The amount of blood taken during a blood test will depend on what is being tested and how many things your doctor is testing.
Blood-sugar levels only require a small drop of blood, but for testing for any diseases such as HIV, HPV, Hepatitis, Syphilis, more blood will need to be drawn.
Fortunately, new smaller test tubes allow for even less blood to be drawn for lab tests, without affecting results. Researchers conducted tests that found smaller tubes meant less blood was needed for testing:
The researchers calculated that in 1 week, 375 tests were ordered that would have required 3750 mL of blood in the formerly used red-top 10 mL tubes, or 187.5 mL of blood per patient. In contrast, gold-topped tubes needed just 3.5 mL, or a total of 1312.5 mL, sparing 2741.5 mL of blood.
Source: Medscape
