Why do blood donation centers bother with platelets?
August 17, 2018 1:44 PM   Subscribe

I gave a 2-hour platelet donation today and the whole process seemed inefficient. Why do they bother with this instead of just doing whole blood?

I'm not talking about inefficiency for for the donor, though it strikes me that they probably have fewer regular donors for platelets since it takes quite a while. More importantly setting up the whole machine took the nurses a very long time, and the amount of time I spent in the chair could have been used by several whole blood donations. Is it really much more efficient to get platelets this way rather than separating them out of a whole blood donation that takes much less time and potentially less of their employees time?
posted by Tehhund to Health & Fitness (16 answers total) 6 users marked this as a favorite
There are only a small number of platelets in a normal blood donation, they can extract up to 4-8 times the amount of platelets the way they did with you today. So despite the time it takes it's still more efficient and they don't have to use blood that could have other purposes to make the platelets. Also you can make platelet donations more often as they return to you the parts of the blood they don't need. So if you were to go in twice a week you could provide as many platelets as 16 people in a week. Where as they'd have to get 16 individual donors in who would have to wait 56 days between donations to get the same number of platelets from whole blood.
posted by wwax at 1:54 PM on August 17, 2018 [25 favorites]

The platelet also lives for a much shorter period of time, about a week compared with 4 months for red cells, so they have to be processed much more quickly. Just a very different product.
posted by wnissen at 2:25 PM on August 17, 2018 [4 favorites]

Also patients who need platelets often only need platelets, not a whole blood transfusion (this is common for cancer patients since chemo is so hard on platelets), so you donating just platelets and getting back the rest means they don't have to post-process your donation to remove components.

Now, whenever I've done apherisis donation, I've made an appointment in advance and the machine has been ready for me as soon as I'm done with the screening, so maybe you got there on a bad day. Yes the donation takes longer, but I've never had to wait in line so clearly most blood centers are able to handle multiple types of traffic without too much trouble.
posted by Lyn Never at 2:27 PM on August 17, 2018 [6 favorites]

It was explained to me that there's a small risk of incompatibility between the donor and recipient, which can lead to complications. (I don't remember the exact details.) When I donate, I can usually give a triple, so someone who needs 3 units of platelets can use my whole donation, and have only one chance at that incompatibility. If that same quantity of platelets came from whole blood, it could have been the product of 20+ donors, so the chance of incompatibility is that much greater. Some cursory googling on single-donor platelets versus multiple-donor platelets indicates to me that there may be an increased effectiveness of single-donor platelets, but I have only a layman's understanding of the science.

Additionally, as wwax notes, even though they may have a smaller pool of donors, those donors can donate more frequently (7 days between donations/24 donations per year is the Red Cross limit), so the total amount collected can be much higher than from whole blood.
posted by yuwtze at 2:28 PM on August 17, 2018 [4 favorites]

Now, whenever I've done apherisis donation, I've made an appointment in advance and the machine has been ready for me as soon as I'm done with the screening, so maybe you got there on a bad day.

My experience has been the opposite. They never set up the machine before I'm screened, and I asked about it once. Each kit is something like $200, and they don't want to prep it unless they know it's going to be used right away. So if you fail the screening, they aren't out a kit.

On the other hand, I've never waited more than 10 minutes for the apherisis machine to get set up, once the screening is done.
posted by Gorgik at 3:32 PM on August 17, 2018 [1 favorite]

Gotcha - so they get many more platelets per donation, and individuals who give platelets regularly can give much more often than whole blood, so even if they have fewer donors they're able to get more platelets this way than from whole blood. And since platelets have a shorter shelf life than the other major blood products, it's worthwhile to dedicate the resources. Makes sense.
posted by Tehhund at 3:54 PM on August 17, 2018 [4 favorites]

Hey, this might get deleted as not answering your question, but...

My dad has leukemia, so far resistant to the (3) different courses of treatment they have tried. His real problem is that he has not enough platelets, and they are not sure what's causing that. As his platelet count fell ever lower, his doctor told him that he could bleed out if it was 10k/microliter of blood (normal range is 150-450k/uL). Well, his count dipped below that number, and they gave him donor platelets (maybe yours). Right after an infusion, his count is about 50k/uL, the next week it's about 25k/uL, then the third week it's... time for another fill-up. He is otherwise asymptomatic, if not exactly the picture of health; he is walking around and being my dad (among other things).

(Nobody will accept my blood, unfortunately -- I am not allowed to donate.)

I couldn't tell you why they do platelet donation the way they do, and I hope the answerers above are right when they say it is not usually quite so inconvenient to the donor. I can tell you that platelet donations specifically and nothing else are what is keeping my dad alive. So thank you.
posted by pH Indicating Socks at 3:54 PM on August 17, 2018 [50 favorites]

Patients can become refractory to platelets. This means that their bodies destroy the platelets as fast as you can transfuse them. I have seen patients on continuous “platelet drips” because of this. Exposure to multiple donors makes this more likely to happen.

Back when I was a new nurse I gave platelet transfusions to oncology patients. It would be 10 little bags from 10 separate donors. We would push them in with a syringe and flush each bag with saline to get as much as possible from each one. And the patient was exposed to the antibodies from 10 donors. But that’s all we had back then.

With pheresis platelets it’s one donor, one bag, and one set of antibodies. And a lot less work to administer.

Bless you for donating!
posted by SLC Mom at 4:33 PM on August 17, 2018 [9 favorites]

Hello from your friendly neighborhood hematologist! Thank you for donating platelets! As attested to by pH Indicating Socks, platelet donations are vital to keeping our patients safe. As you may have heard, platelet donation can be done every 2 weeks, as opposed to whole blood donation, which requires a few months to recover from. But we can only keep donor platelets for 5 days, so we need a constantly replenishing supply.

There are two types of donor platelet products. Pooled platelets are spun down from whole blood units, and these concentrates are combined with 4-6 other whole blood donors. The actual number of platelets in a pooled unit varies by how many platelets are in each collected whole blood unit.

The second type is single donor platelets - what you did, which is platelet collection by apheresis. A centrifuge runs on the blood and pulls the platelets out, and then returns RBCs and plasma back into the donor. We are able to get the same number of platelets from a single-donor aphaeresis session as would be collected from six whole blood donors.

Recipient benefit of aphaeresis donation is a theoretical lower risk of infectious disease exposure (important in immunocompromised patients, although this risk is already very low). Also fewer donor antibody exposures (as SLC Mom has alluded to). It also allows for some different matching for patients that may be refractory - you can't HLA match pooled platelets. It is more expensive - apheresis is notoriously expensive. It's inconvenient for donors, as you have realized. Overall, though, for most patients, pooled vs. apheresis is about equivalent for the recipient.
posted by honeybee413 at 5:00 PM on August 17, 2018 [10 favorites]

A bit tangential, but: The apheresis process does something weird with the calcium in your blood. Extracts and then returns it, perhaps? Anyway, many people are unable to donate platelets because of that even if the time commitment isn't a problem for them. When I tried it, after donating more than a dozen gallons of whole blood through the years, I got very "buzzy" and agitated, and they had to stop. They said my reaction was quite common. It was such a shame, but I just couldn't do it.
posted by DrGail at 5:00 PM on August 17, 2018 [1 favorite]

Dr. Gail, the apheresis circuits are kept open using a citrate-based anticoagulant. Because of the nature of apheresis, some of this gets into the bloodstream. This chelates calcium and can cause hypocalcemia.

When I do therapeutic apheresis in the hospital, i typically administer calcium gluconate to prevent the symptoms you describe, but I can see how an outpatient blood donation center would not have this option.
posted by honeybee413 at 7:51 PM on August 17, 2018 [5 favorites]

(Nobody will accept my blood, unfortunately -- I am not allowed to donate.)

Me neither - Mad Cow Club. But I did receive blood once, so thank you all who donate.
posted by The Underpants Monster at 8:01 PM on August 17, 2018 [4 favorites]

I tried to give platelets once. Something went weird - i had a half tennis ball sized lump on my arm under the gauze while the process was happening. They made clear the platelets were more useful but that i personally should only give a whole donation of blood. This led me to believe that platelets were preferred but not everyone could do it, so those who could should keep giving that way.
posted by I'm Not Even Supposed To Be Here Today! at 8:46 PM on August 17, 2018 [1 favorite]

I give platelets regularly and feel like I am doing something very worthwhile every time I do it. I know that they are badly needed and can't be stored and it's kind of the only body part I have to offer that's at all desirable. My blood is B+ so not particularly in high demand.

My experience is that the interview, hemoglobin test, bp and pulse check, and setting up the chair all together take about 30 mins. But I get it that a good deal of this time is about patient safety. Setting up the bags in advance seems like it carries some risk, as opposed to getting a fresh single use pack and opening it while the donor is already in the chair.

I have a ton of platelets and am cleared to give every two weeks, but my hemoglobin doesn't seem to refresh as quickly so it's not unusual for me to come to my appointment and leave without donating. Talk about a waste of time! It can be really frustrating. My donation center knows now to check my hemoglobin before doing anything else. I also take a couple of tums daily for the few days leading up to my appointments because in prone to foot cramps and if I don't supplement my calcium, I have a much higher risk of a charleyhorse while donating.

So yeah, it can be time consuming. But that fat juicy bag of platelets is worth its weight in gold and I get cookies and juice afterwards.
posted by janey47 at 12:47 AM on August 18, 2018 [6 favorites]

For a stretch I did platelet pheresis every other Tuesday. I donated jillions of the damn things, and I talked to the blood bank staff a lot.

There are lots of reasons that it is a vital product, so some overhead in the process is acceptable. When each bags is four units, the same amount of time for prep is divided by four — and that’s very little time per unit.

The more often you go, the quicker you move through the screening & prep. And when you’ve proven to have a short recovery time (from the minimal fluid loss), you don’t have to hang around so long afterwards.

I am also in the too-long-in-Europe/UK club, so I haven’t donated blood or platelets in a disappointingly long time.
posted by wenestvedt at 4:56 PM on August 18, 2018 [2 favorites]

The only downside to frequent platelet donation is that eventually you own mutiples of all the gifts that the blood bank gives out!

Before they stopped accepting me, I had two pairs of shorts, four or five mugs that showed a message when they got hot, two different umbrellas, and TONS of other stuff.

The one I like best is the one that got me to donate first though (I am so shallow): a t-shirt with a saint bernard dog on it that says Platelet Rescue Squad. I still wear it once in a while, too.
posted by wenestvedt at 6:05 PM on August 18, 2018

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