Matching Kidneys

I was searching teh internets for something to write about and I came across this cool game about living kidney donors from Liberty Science Center. Receiving an organ from a living donor has an 84% success rate, compared to a 54% success rate from deceased donors.

Finding a kidney recipient is a little different then with the other organs. Because the person who needs a kidney can be maintained on dialysis, kidneys are matched not only by blood type but also with with tissue markers, similiar to the way people are matched for bone marrow transplants. This applies to pancreata as well-don't mean to exclude you pancreas people, I'm just trying to keep things simple.

See, if you need a heart, chances are you need one really soon or you're going to die. So you transplant surgeon is going to be looking at the donor's blood type, height and weight. You can't put a linebacker's heart into a petite woman, for example. There are other considerations, obviously, like risk factors and heart function, but if your patient has only days to live, blood type, height and weight are the big three.

Because of dialysis(or insulin therapy for the pancreas), a patient can be maintained until a "perfect" organ becomes available. Actually, there is no "perfect" kidney match. According to my lab director, there are HLA markers that haven't even been discovered yet, they just know they're out there. So, there are six markers that are looked at in matching kidneys and pancreata. If the recipient and the donor share all six, it's called a "zero mismatch". That means they all match, hence NO mismatches. Why don't they just say it's a "six match". Because the HLA never perfectly matches up, due to all the subgroups or something. Dammit Jim, I'm a transplant coordinator, not a biochemist.

Why is this so important? Because an organ with a zero mismatch will last longer and work better. Extending the life of an organ means less chance or rejection, less chance of needing to be retransplanted and less people back on the waiting list. This is why using a living donor is prefered for kidneys. Obviously, only with kidneys, unless you live in China. But that's another post. The easiest way is to find a family member that is compatible. Since you get half your markers from you mom and half from your dad, it is most likely that a sibling will have the same markers as you. 25% chance or matching from a sibling, unless you're identical twins-which is how the first successful kidney transplant was done. But what if you don't have a sibling, let alone an identical twin. What if no one in you're family is a match?

One solution is using a paired donor exchange. Say my daughter needs a kidney but I don't match her. Then say another person needs a kidney and their brother doesn't match him. But his brother matches my daughter and I match with him. We would then donate our kidneys to each other. These programs are usually done at transplant centers and they're being studied, not only for their success rates for also for ethical considerations. Just a few things to think about. Maybe sometime I'll write about the evils of black market kidneys.