To get around this, they supposedly dilute the samples to a point where the concentrations of analytes are well below the machines minimum operating specifications.
2) Theranos invents a new low volume blood draw technology and test mechanism (which contains many subtests)
3) The test they use to augment their limited test is a commercial product that works on larger volumes of blood
4) because their test doesn't actually work all that well (I actually don't know enough about this part, as their work is mostly secret) they have to pivot a bunch of of their tests to using a different company's test machine
5) Those other commercial products actually do work with smaller volumes of blood, diluted to larger volumes, in case you can't get a large volume from a patient
There isn't anything wrong with Theranos diluting blood to make their tests work with another commercial product (this is a legitimate use). However, it does seem to suggest that the technology that hyped Theranos up to a multibillion value isn't as good as was claimed; instead, Theranos is mostly just another conventional provider of diagnostic tests. If they're just another conventional provider, it sort of kills the whole startup story and investment, because why would you invest in a disruptor if you can make money from the establishment?
That said, it's common to see startups start with a really ambitious goal, fail, then pivot to become more conventional companies with decent but not spectacular revenue streams.
This is like if every time you fetched an Uber, a yellow cab showed up! Except for one market out of 200, where they run five black cars, in a small SF neighborhood.