Matchmaker, Matchmaker, Make Me a Match

GREAT NEWS! I got a call from Northwestern today confirming that Phase 1 of testing is complete, and I am eligible to donate as soon as I am matched to a recipient. This should happen inside the next 6 months!

If you are donating a kidney, it is ideal to be type O, if you need a kidney, it is ideal to be AB.  I am A+ (not ideal), so my recipient will need to be A+ or AB+.  On rare occasions A’s can also donate to O’s.  Here is a table that explains who can donate to who.


I find that this table is helpful to look at next, so you can determine the approximate percentage of the population that you can donate to, or receive from.

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To be a match, several medical fronts need to align between the recipient and me to make sure we are compatible. Things like age, weight, and a laundry list of biological markers are considered when making a good match. The closer the match, the more likely it is that the recipient won’t reject my kidney once it is transplanted. This happens about 15% of the time in the first year after transplant, and is caused by the recipient’s immune system attacking the foreign organ. So the goal is to minimize the opportunity for the immune system from doing this by creating a good match from the start, and then giving the recipient anti-rejection drugs after the transplant (for life).

First, the recipient needs to have their antibodies measured so that their  Panel Reactive Antibodies (PRA) can be calculated.  PRA is measured from 0-100; the lower your score, the easier it is to get a suitable donor.  The cPRA estimates the percentage of donors with whom a particular recipient would be incompatible. In other words, it would give you an idea of the percentage of offered kidneys your body would likely reject at the time of transplantation. People who have previously had a transplant and/or a blood transfusion are more likely to have a higher number.  Interestingly, women who have had children often have a higher score as well.  The common thread is having had somebody else’s parts (blood, organ, fetus), in your body.  Over time, patients develop antibodies against those proteins, and once they’re in the system, they don’t go away—meaning they’ll be more likely to attack foreign proteins from a new transplant.

According to the National Kidney Foundation, “Patients with high cPRA levels get priority for transplantation because it is harder to find compatible donor organs in those situations. The good news is that most patients awaiting kidney transplantation have low levels of anti-HLA antibodies, but it is estimated that 9,000 patients on the waitlist have cPRA > 95%.”

Next, the doctors will do a cross match with my blood and the potential recipient’s blood.  This means they mix a vile of my blood with a vile of the recipient’s blood, and watch to see if the blood likes each other.  The test will be positive or negative.  You want it to be negative.  A positive result  means that the recipient’s blood is fighting my blood, and we are not a compatible team 😦

Lastly, there is something called leukocyte antigens that they look at. These are markers that appear on the surface of immune cells, commonly used to determine compatibility between organ donors and recipients. Ideally, the donor and recipient would have the exact same set of 6 antigens, since any unfamiliar antigen will invoke an immune reaction (like an allergic reaction). Identical twins are the only cases that have the exact same set, so since I am not donating to a twin, second best is to find a match with a lot of overlap.  Statistically, the life of the transplanted kidney will be longer the more overlap we have between our leukocyte antigens.

In a nutshell, this testing is pretty complex, and lots of smart people will use a computer system and complex algorithm to make sure they come up with a good match.  Just because the match looks good on paper doesn’t mean that the recipient does not have antibodies to my antigens. If our blood mixes well, we can be matched for donation.

The donation can happen at anytime now. We are shooting for late August or September, but if they can initiate a long chain before then, I will do it sooner. The time frame is partly selfish- I don’t want to cut into boating season or get a post-opt hernia from bouncing around on the river 🙂

So until then, I’ll continue to research fun stuff and keep the posts coming! Thanks for reading!


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