I’ve heard of PCR before (polymerase chain reaction) where more copies of a DNA sample can be rapidly made. If the problem was that the quantity of blood that Theranos uses is too small, why wasn’t PCR used/ (if it was) why didn’t it work?
Also if I’m completely misunderstanding PCR, if someone could for that too, I’d appreciate it, thank you!
In: 148
Abbott Diagnostics makes a device called an [iStat ](https://www.globalpointofcare.abbott/en/product-details/apoc/i-stat-system-us.html?gclid=CjwKCAjwzeqVBhAoEiwAOrEmzdgAlrkpwgFsIetgEIUdu4NDZYxk1kBCkA6D4C2LXCG2KRndojK2xxoC6FIQAvD_BwE), which actually does a lot of what Theranos aimed for: microfluidic system, small sample volumes, point of care tests, etc. iStat has been on the market for decades, and fills a very good niche role. It’s a lot more expensive and time consuming to do tests in bulk on an iStat, but it’s great when you need one result right now.
Two big limitations on this tech: when you draw someone’s blood, you break a lot of cells, and the stuff inside the cells can throw off some of your tests because it’s different than the stuff inside your blood. If you use a larger tube of blood, that stuff is diluted out enough that it doesn’t affect the results.
The other one is sensitivity. The most sensitive PCR test in my lab needs at least ten viruses per ml in the specimen to accurately detect it. So if I take that kind of sample and split it into 0.1 ml tubes, each tube would only have an average of 1 virus per tube. If I split it into 0.05 ml tubes, half of the tubes statistically wouldn’t have any virus at all, so if I run that on an instrument, it will return a negative result.
I’ve heard of PCR before (polymerase chain reaction) where more copies of a DNA sample can be rapidly made. If the problem was that the quantity of blood that Theranos uses is too small, why wasn’t PCR used/ (if it was) why didn’t it work?
Also if I’m completely misunderstanding PCR, if someone could for that too, I’d appreciate it, thank you!
In: 148
Abbott Diagnostics makes a device called an [iStat ](https://www.globalpointofcare.abbott/en/product-details/apoc/i-stat-system-us.html?gclid=CjwKCAjwzeqVBhAoEiwAOrEmzdgAlrkpwgFsIetgEIUdu4NDZYxk1kBCkA6D4C2LXCG2KRndojK2xxoC6FIQAvD_BwE), which actually does a lot of what Theranos aimed for: microfluidic system, small sample volumes, point of care tests, etc. iStat has been on the market for decades, and fills a very good niche role. It’s a lot more expensive and time consuming to do tests in bulk on an iStat, but it’s great when you need one result right now.
Two big limitations on this tech: when you draw someone’s blood, you break a lot of cells, and the stuff inside the cells can throw off some of your tests because it’s different than the stuff inside your blood. If you use a larger tube of blood, that stuff is diluted out enough that it doesn’t affect the results.
The other one is sensitivity. The most sensitive PCR test in my lab needs at least ten viruses per ml in the specimen to accurately detect it. So if I take that kind of sample and split it into 0.1 ml tubes, each tube would only have an average of 1 virus per tube. If I split it into 0.05 ml tubes, half of the tubes statistically wouldn’t have any virus at all, so if I run that on an instrument, it will return a negative result.
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