Would you mind including those? As a non medical expert, nor physicist it doesn't seem implausible that medical testing can be improved 10x from where it is and many other competitors to Theranos seem to be raising capital (Healthtell >25M recently) so the consensus doesn't seem to be insurmountable && obviously scientifically impossible. Again, I am not favourably comparing Holmes to Musk, but it is narrowly physically possible to go to mars, certainly we have a bit more clarity on local testing of blood.

> Several studies suggest that small volumes of blood have too much variance to yield useful test results.

That's misrepresenting it a bit. Currently there are zero blood tests that have a 100% accuracy therefore if you can't do a normal test with an accuracy near 100% you're not going to be able to do it with a smaller subset of data.

However, if we get to the point of 100% accuracy (or at least near) then there is no reason why those types of tests couldn't be useful. But yes today they are not.

It's also possible to question the idea the idea that are testing leads to better outcomes in the first place.

It's not 'we have no idea how to do this' impossible, it's physically and technically impossible?

Judging from what I read in comments on Derek Lowe's blog, the problem is not so much being able to do blood tests on µL of blood (which I suspect we might have the technology to do; whether it's cost-effective is a different question) but rather that the way you get only a little bit of blood screws up the results--you're extracting more from capillaries than veins, and you get more contamination from skin and other tissue cells.