[kneel]

It's not obvious that the diagnostic assays they were running couldn't scale down.

These assays are performed regularly on large samples no problem, but the sensitivity and accuracy of the assay becomes erratic when you only have a couple micro liters of blood.

Either they couldn't develop proper assays (an engineering problem) or microliters of blood don't contain enough substrates for their assays (a major lapse in knowledge)

[hga]

It's more like the method of drawing the blood was thought to be the problem. A venous draw is going to be pretty clean, in that whatever tissue got stuck in the aperture of the needle is going to be dwarfed by the quantity of blood taken; I've read that the actual assaying machines use very little of the blood, which makes sense because the reagents used are expensive, plus to the extent you're using optical scanning to read the results (what else might you use?), thinner will tend to be better (note most of the preceding is WAGs on my part from basic principles).

Whereas a fingerstick produces a few drops of blood that flow to the surface moving past the tissue and cells that were cut getting to the blood vessels, and they'll contribute unrelated proteins, lipids from cell membranes, etc. etc. On its face, many many people have said this is so problematic real evidence that it worked was needed; heck, even a theory would have been nice, but neither were forthcoming.

[vonmoltke]

> A venous draw is going to be pretty clean, in that whatever tissue got stuck in the aperture of the needle is going to be dwarfed by the quantity of blood taken

From the many blood draws I have done, standard practice is to fill a tosser vial before collecting the real samples in order to remove these contaminants.

[hga]

From the ones done on me for bog standard tests in the last dozen years or more, that wasn't done, but the extra gunk in the vial just might be intended to grab the contaminants as well as stabilize the blood. Or maybe these more standard tests allow for whatever amount of contamination is in the drawn blood, suppose it's 2-3 orders of magnitude less.

[madgar]

They don't throw out the first vial right there in front of you.

[hga]

When they only take one vial, they'd better not be throwing it out and sending my doctor and myself "results"!

Now, it's possible I'm mis-remembering this, although the protocol includes showing me the vial after the draw so I can confirm it's labeled correctly and I tend to remember additional vials, since that manipulation often hurts more than anything else. I'll pay attention, heck, ask the phlebotomist in a few months during my next annual checkup.

[joezydeco]

...optical scanning to read the results (what else might you use?)

There's been some research into using piezoelectric elements coated with antigen or other reactive surfaces.

A positive result (meaning antibodies are attaching themselves to the substrate) would change the resonant frequency of the surface.

http://www.sciencedirect.com/science/article/pii/S0003267000...

[mk1202]

There are a couple of companies doing the same thing. They seem legit, and are founded by PhDs and university research scientists. If you look at their websites, you will find details about their technology, publications in scientific journals, professional conference talks & awards, etc. But they are not well known or hyped as much as Theranos.

http://www.cbc.ca/news/canada/british-columbia/uvic-blood-te...

http://www.siscapa.com

http://www.genalyte.com

[joezydeco]

It was obvious to a great number of other diagnostics firms that this technology was hard to scale down.

I was at one of those firms 25 years ago and they were working on it back then. Either they abandoned the effort, or are still trying, but they haven't launched a single microfluidic immunoassay.