Drawing blood twice in 2 days— problem?
May 28, 2016 4:25 AM   Subscribe

Two doctors asked me to perform blood tests. I unthinkingly decided to do them two days in a row— one on Thursday and one yesterday. I didn't tell the second nurse that I had just had my blood drawn the previous day. Is it dangerous to have blood drawn twice in two days? Less importantly, could it mess up the results from my second blood draw?

If it's relevant, the first blood draw was for my annual physical and the second was to monitor the effects of a new medication dosage. YANMD.
posted by I made this account so Matt could have a $5 beer to Health & Fitness (10 answers total)
You are fine. No worries.

A lot of times running two blood tests just means pulling two vials of your blood, because they're running different analyses which may require different prep or even take place in two different locations. Odds are that they would have grabbed two vials from you Thursday if they had done them at one time.

My personal record for "max blood drawn by doctors at one time" is I think 7-8 vials? Which is still pretty low compared to some folks I know. Don't sweat it.
posted by pie ninja at 4:29 AM on May 28, 2016 [4 favorites]

My last physical involved about 10 vials of blood in one go.
The one before that was the same number, but I had to chase all over town and get it done in multiple visits over 2 days because no single lab had all the right tubes for the tests I needed. Argh.
So, I think you're fine.
posted by Metasyntactic at 4:30 AM on May 28, 2016

It was 2-4 vials of blood each time, so I think you are all right and I am well within the safe threshold. Thinking about it a bit more, I think it's still far less than a pint of blood (57 vials, apparently!) which is the standard amount one draws for a donation.

Duh. I haven't had a lot of medical work done before, so I panicked a little bit. Thank you!
posted by I made this account so Matt could have a $5 beer at 4:36 AM on May 28, 2016 [1 favorite]

I have had tests where they draw blood three times in one morning, an hourly intervals. It's fine.
posted by kitten magic at 4:38 AM on May 28, 2016

My wife got her phlebotomy license recently, and she says you almost certainly don't need to worry. There is a condition known as iatrogenic anemia that can be induced by drawing too much blood for tests, but it's only a real concern for hospitalized patients (whose blood is being frequently tested) and for infants (who don't have much blood to begin with. She also notes that when she was taking her phlebotomy classes, she and her fellow students would do practice blood draws on each other for multiple days in a row, without ill effect.
posted by Johnny Assay at 5:30 AM on May 28, 2016 [1 favorite]

A standard blood donation bag is 470 ml. A standard blood test vial would be 10 ml.
posted by wilful at 6:05 AM on May 28, 2016 [2 favorites]

Add me to the list who have had 10 -actually I think 12 vials at once early in the morning on an empty stomach. Other than the symptoms I was being tested for and being tired and hungry I was fine. And I'm a very petite lady who wouldn't be able to donate blood. The only thing that may be useful is switching arms they draw from of you're sore or bruise easily but that's just for comfort.
posted by Crystalinne at 6:38 AM on May 28, 2016

In the hospital they'd draw your blood like every day sometimes, so you'll be fine.
posted by limeonaire at 7:37 AM on May 28, 2016 [1 favorite]

IAASN, NARN (I am a student nurse, not a real nurse)!

As everyone says, you are totally fine and will not likely suffer any ill effect. To respond to the part of your question about whether this could change your test results, you are fine there too. There are blood tests which require that the blood used be the first drawn, or not the first drawn, from a given site; but there are no tests requiring that there have been no other tests recently as far as I know.
posted by snorkmaiden at 7:56 AM on May 28, 2016 [2 favorites]

I AM a Real Nurse, and I'm nth-ing that you're totally fine. Many conditions and tests require repeat blood draws over short periods of time (for example, one common method of testing for gestational diabetes in pregnant women). It's common and harmless in an otherwise generally healthy person. If you're severely anemic, have some sort of blood dyscrasia, or are a Jehovah's Witness, I'd recommend requesting pediatric tubes or at least double-checking with the ordering physician, if only for peace of mind. Otherwise, absolutely no problem.
posted by pecanpies at 9:48 AM on May 28, 2016 [1 favorite]

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