…it is impossible to get a precise result from the tip of a finger for most of the tests that Theranos would claim to conduct accurately. When a finger is pricked, the probe breaks up cells, allowing debris, among other things, to escape into the interstitial fluid. While it is feasible to test for pathogens this way, a pinprick is too unreliable for obtaining more nuanced readings. Furthermore, there isn’t that much reliable data that you can reap from such a small amount of blood.
Don’t be surprised if jail time is a-coming for some of the hire ups of the company, Holmes in particular.
http://www.vanityfair.com/news/2016/09/elizabeth-holmes-theranos-exclusive