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Taking a vial of blood prior to a finger prick blood test could dramatically alter results. Further, when the baseline (i.e. other labs) also have varying resul

Taking a vial of blood prior to a finger prick blood test could dramatically alter results. Further, when the baseline (i.e. other labs) also have varying results, its fair to call into question the whole study. Although I have my doubts Theranos blood tests are as acurate, I feel the study was pretty flawed.

cordite 11y ago
Sounds like time for randomized sequencing. Basic Stats 101.
0xffff2 11y ago
>Taking a vial of blood prior to a finger prick blood test could dramatically alter results. Could you elaborate on why? My expertise is limited to an EMT certification that expired half a decade ago, but isn't obvious to me why this would be the case. Blood is constantly circulating, and even a veinous blood drawn doesn't remove an appreciable amount of blood compared to the total flow.
- lettergram 11y ago
  Besides a plethora of things that can occur[1], the main issue is a combination a pain response and a foreign object entering the skin. When a you stick a needle in a persons arm you often trigger a flight-or-flight repsponse. It's actually fairly similar if you prick their finger. The problem with this study is that one was done after or before the other. It depends what you look for, but for example white blood count (which was tested) would/should change subtly after a blood draw. The amount can vary (or not vary) depending on the person. For example, when I get my blood drawn my arm swells, it's not actually that I am allergic, but my body reacts in said way. Regardless, my only comment was that the study seemed to be on somewhat shaky footing. [1] http://www.frhg.org/documents/Lab_Manuals/Blood-Collection-Adverse-Reactions-and-Patient-Blood-Volumes.pdf http://www.frhg.org/documents/Lab_Manuals/Blood-Collection-A...
paddlepop 11y ago
The vial of blood was only taken before the finger prick in the morning testing, in the afternoon testing the vial of blood was taken after the finger prick. While it would have been nice to have them mix up the before/after scenarios between morning/afternoon it would be interesting to see if this has any effect in the raw data. I would guess it would have little effect as the volume of blood in a vial is still relatively trivial.
tclmeelmo 11y ago
> Taking a vial of blood prior to a finger prick blood test could dramatically alter results. Interesting. What mechanism or phenomenon are you proposing would be happening? Why do you think sampling order has more influence than the sample method (venipuncture v. finger prick)? > Further, when the baseline (i.e. other labs) also have varying results, its fair to call into question the whole study. Why? That's an expected outcome when dealing with multiple testing labs.
todd8 11y ago
Every time I've had blood drawn it has taken several minutes and required a number of vials; if order was important it seems that it would be affecting the results of conventional blood testing. For me at least, the actual drawing of the blood is anti-climactic and I experience the most anxiety (with it's concomitant physiological reactions) in advance of the blood being drawn at all. Consequentially, it seems likely that the order doesn't matter significantly. Furthermore, it's hard to imagine how results could be dramatically altered. How would having a previous finger prick blood test for say glucose level, cholesterol, triglycerides, blood count (CBC), calcium levels, blood urea levels, or the presence of antibodies possibly change the results of a subsequent test?

cordite 11y ago

Sounds like time for randomized sequencing. Basic Stats 101.

0xffff2 11y ago

>Taking a vial of blood prior to a finger prick blood test could dramatically alter results. Could you elaborate on why? My expertise is limited to an EMT certification that expired half a decade ago, but isn't obvious to me why this would be the case. Blood is constantly circulating, and even a veinous blood drawn doesn't remove an appreciable amount of blood compared to the total flow.

lettergram 11y ago
Besides a plethora of things that can occur[1], the main issue is a combination a pain response and a foreign object entering the skin. When a you stick a needle in a persons arm you often trigger a flight-or-flight repsponse. It's actually fairly similar if you prick their finger. The problem with this study is that one was done after or before the other. It depends what you look for, but for example white blood count (which was tested) would/should change subtly after a blood draw. The amount can vary (or not vary) depending on the person. For example, when I get my blood drawn my arm swells, it's not actually that I am allergic, but my body reacts in said way. Regardless, my only comment was that the study seemed to be on somewhat shaky footing. [1] http://www.frhg.org/documents/Lab_Manuals/Blood-Collection-Adverse-Reactions-and-Patient-Blood-Volumes.pdf http://www.frhg.org/documents/Lab_Manuals/Blood-Collection-A...

paddlepop 11y ago

The vial of blood was only taken before the finger prick in the morning testing, in the afternoon testing the vial of blood was taken after the finger prick. While it would have been nice to have them mix up the before/after scenarios between morning/afternoon it would be interesting to see if this has any effect in the raw data. I would guess it would have little effect as the volume of blood in a vial is still relatively trivial.

tclmeelmo 11y ago

> Taking a vial of blood prior to a finger prick blood test could dramatically alter results. Interesting. What mechanism or phenomenon are you proposing would be happening? Why do you think sampling order has more influence than the sample method (venipuncture v. finger prick)? > Further, when the baseline (i.e. other labs) also have varying results, its fair to call into question the whole study. Why? That's an expected outcome when dealing with multiple testing labs.

todd8 11y ago

Every time I've had blood drawn it has taken several minutes and required a number of vials; if order was important it seems that it would be affecting the results of conventional blood testing. For me at least, the actual drawing of the blood is anti-climactic and I experience the most anxiety (with it's concomitant physiological reactions) in advance of the blood being drawn at all. Consequentially, it seems likely that the order doesn't matter significantly. Furthermore, it's hard to imagine how results could be dramatically altered. How would having a previous finger prick blood test for say glucose level, cholesterol, triglycerides, blood count (CBC), calcium levels, blood urea levels, or the presence of antibodies possibly change the results of a subsequent test?