[2YwaZHXV]

OK, so these are more business reasons for bigger samples than technical reasons.

1. Ok, so that can still be done with small samples, it's just a matter of collecting enough. The link I gave showed 15 tests in 30ul of sample. So, 60ul would be enough for your 30 tests. The amount used per test (for many many tests) is still very small compared to the amount drawn.

2. I imagine if a tube is dropped and some sample is lost they consider the whole sample lost. Since if sample got out that also means that stuff can get in, possibly contaminating it. The poor customer experience of having to go back in to be re-drawn is a poor business choice, but again, not a technical hurdle with being able to perform tests. Having enough sample for re-testing a week later is also just a matter of collecting sufficient sample. So, you would need 120+ul of sample (from previous example of 30 tests) to meet that requirement (plus some amount for loss in equipment, etc). But, it is still a far cry from the 2000+ul typically drawn.

3. You actually often have more than 2 drawn, since each tube has a different kind (if any) anticoagulant and if they get sent to different labs they may need duplicates of the same anti-coagulant. This also doesn't have anything to do with the size of the sample required for a test. So, you can collect a bunch of small samples instead of bigger samples. That's not a technical hurdle for being able to perform a test on a small volume of blood.