I heard that the reason why it can't be done is that to get those quantitative measurements you have to react the blood sample with certain chemicals. To do mul

I heard that the reason why it can't be done is that to get those quantitative measurements you have to react the blood sample with certain chemicals. To do multiple tests you need enough blood that you can divide it up into samples and react each one separately. So if you only start off with one drop its hopeless to run the full suite of tests.