Accuracy of Hematocrit finger stick

[snake]

When donating blood, they do a finger stick for crits. I often wondered how accurate that was so I donated on Thursday (47%) and had BW done on Friday morning (51%). So something is off. How could I donate and be 4% higher. Either the finger stick test is off or I may have been a little dehydrated since it was in the morning. I do stay well hydrated so the I'm leaning to the finger stick method is just off.

 

[Yano]

Interweb threw this back at me on a quick search

HCT levels: Normal HCT levels for adult men are 40–54%, and 34.9–44.5% for adult women. HCT levels below 40% can indicate anemia.

Hematocrit tests are "generally accurate" and provide a clear reading of red blood cell levels. However, there are some factors that can affect the accuracy of a hematocrit test, including:

• Hand used
  When comparing capillary blood from the left hand to the right hand, there is high within-subject variability.
  
  
  
• Days between measurements
  When taking measurements on four consecutive days, there is high within-subject variability.
  
  
  
• Equipment used
  The results of a hematocrit test can vary depending on whether a mobile or fixed centrifugation equipment is used.
  
  
  
• Anticoagulant solution
  The results of a hematocrit test can vary depending on the anticoagulant solution used.
  
  
  
• Microhematocrit tube diameter
  The results of a hematocrit test can vary depending on the diameter of the microhematocrit tube used.
  

 

[snake]

• Hand used
  When comparing capillary blood from the left hand to the right hand, there is high within-subject variability.
  
  
• Equipment used
  The results of a hematocrit test can vary depending on whether a mobile or fixed centrifugation equipment is used.
  

I'm going with the equipment on this one.

It's also in the donation centers best interest for crits to be lower so they won't have to turn someone away and not get a pint.

The left hand/right hand thing I'm going to have to look into.

 

[Jonjon]

The finger test is worthless
I went to donate blood while I was in eq. Hemoglobin came back over 20. Guy said “I’m sorry we can’t take your blood”

I said check it again
it came back under 18
He checked a third time and I forget what it was, but it was different than the first two readings. Showed me that it is unreliable.

 

[j2048b]

When donating blood, they do a finger stick for crits. I often wondered how accurate that was so I donated on Thursday (47%) and had BW done on Friday morning (51%). So something is off. How could I donate and be 4% higher. Either the finger stick test is off or I may have been a little dehydrated since it was in the morning. I do stay well hydrated so the I'm leaning to the finger stick method is just off.

Its all bullshit

I went last Thursday and got bloods pulled for 2 different docs, they each wanted their own cbc

Here wrre the differences between probably 2 minutes, same lab same variances but different numbers

Its all total bullshit

The first readings i got back within a couple days… the 2nd one took over a week,

 

[j2048b]

Some say to get hydrated and give blood in the afternoon… but we all know ur viscosity is worse in the am… so who knows…

 

[j2048b]

The finger test is worthless
I went to donate blood while I was in eq. Hemoglobin came back over 20. Guy said “I’m sorry we can’t take your blood”

I said check it again
it came back under 18
He checked a third time and I forget what it was, but it was different than the first two readings. Showed me that it is unreliable.

Hell even the drawing and testing from the arm is unreliable… look at mine taken within minutes apart…

 

[Send0]

Hell even the drawing and testing from the arm is unreliable… look at mine taken within minutes apart…

It's close enough, 3% difference between your 2 tests.

I'm sure someone can find what the acceptable margin of error on a CMP is. I'd be interested if anyone had that information to share

 

[snake]

Its all bullshit

I went last Thursday and got bloods pulled for 2 different docs, they each wanted their own cbc

Here wrre the differences between probably 2 minutes, same lab same variances but different numbers

Its all total bullshit

The first readings i got back within a couple days… the 2nd one took over a week,

Wow! Let me make sure I have this right. You had BW drawn for 2 different Dr. within 2 min of each other and it was about 3% different? Both from an arm?

 

[j2048b]

Wow! Let me make sure I have this right. You had BW drawn for 2 different Dr. within 2 min of each other and it was about 3% different? Both from an arm?

Yeah… same arm same everything…

even 3% difference is kind of shocking considering all they did was change out the tube… i dont feel anything should have changed… but like @Send0 said maybe we can find out what the acceptable margin of error is?? But it is odd to me

 

[snake]

Yeah… same arm same everything…

even 3% difference is kind of shocking considering all they did was change out the tube… i dont feel anything should have changed… but like @Send0 said maybe we can find out what the acceptable margin of error is?? But it is odd to me

Thanks for clarifying that. Yeah 3% isn't much but there's a point where a Dr. is going to take issue with it. 50%, maybe the Dr. doesn't say much, at 53% he may comment. And ultimately you want the correct number, especially if you're trying to address a potential problem.

 

[Send0]

Yeah… same arm same everything…

even 3% difference is kind of shocking considering all they did was change out the tube… i dont feel anything should have changed… but like @Send0 said maybe we can find out what the acceptable margin of error is?? But it is odd to me

It is kind of crazy that there was any difference given that it was taken 2 minutes apart. That's what got me thinking about what the standard margin of error is on these panels.

@BRICKS do you have any insight into what is considered an acceptable margin of error on blood panels? Specifically CMP?

 

[Reader591]

I once had it taken 3 times just minuets apart. It was different each time by a somewhat substantial amount in my opinion. I’ve since thought it’s more of a ballpark figure then super reliable

 

[j2048b]

Thanks for clarifying that. Yeah 3% isn't much but there's a point where a Dr. is going to take issue with it. 50%, maybe the Dr. doesn't say much, at 53% he may comment. And ultimately you want the correct number, especially if you're trying to address a potential problem.

Exactly the first round i was like cool… need to hydrate and ip6… then i got the 2nd blood work done and i was like shit thats the one going to my main urologist… who scripts me test and wants me on a phlebotomy…

 

[j2048b]

It is kind of crazy that there was any difference given that it was taken 2 minutes apart. That's what got me thinking about what the standard margin of error is on these panels.

@BRICKS do you have any insight into what is considered an acceptable margin of error on blood panels? Specifically CMP?

Could be the travel the vials took as well? One could of gotten heated up more perhaps? Sat longer? Who knows …

 

[Kraken]

The Red Cross stuck my finger today, came up with 20.1. Stuck a finger on the other hand, 20.1 again. At least its consistent. Either way they didn't want my blood. But, I wonder if 20.1 is just the highest number?