Someone with a PhD in microbiology explained to me (a layman) why what Theranos was claiming to do was impossible. She said you cannot test only a single drop of blood for certain things because what you are looking for literally may not be there. You need a full vial of blood to have a reliable chance of finding many things.
1. Is this simple but clear explanation basically correct?
2. If so, how could Theranos hoodwink investors for so long when possibly *millions* of well-educated people around the world knew that what they were claiming to do made no sense?
In: Biology
As a scientist who researches and develops diagnostic tests, I’ll try to concisely answer your first question.
When developing any diagnostic test, it all comes down to sensitivity and specificity. To achieve that, there is a lot of optimisation needed to make sure you accurately detect and measure the one thing you’re looking for.
A box that is able detect and measure hundreds of metabolites from a drop of blood using a single assay is not impossible as this is what mass spectrometers are used for. However, these machines are very complex and expensive. That’s why they are more useful in measuring levels of things that are normally too low and require high sensitivity. On the other hand, they would be a waste of resource for measuring something like cholesterol or blood sugar.
More importantly, there is no one single sample preparation technique for measuring everything in the blood. Some metabolites may be stuck to proteins, some metabolites are inside red blood cells and need to be pulled out, some metabolites are very similar in shape/chemistry, etc. Then again, not everything in the blood is detected using the same detection technique. All that means is a one size fits all approach condensed in a small box that has both a sample prep robot and a detector is practically impossible, but also not something you want to have. It is a maintenance and quality control nightmare.
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