The Truth About Aaron's Numbers

Feb 22, 2020

If I talk to you in person and you ask how Aaron is doing, chances are I will say something like, "He's doing really well. His counts are looking good."

This is true.

His platelets have been in the normal range for months now. He hasn't needed a blood transfusion in twelve weeks. He has neutrophils.

But what I might not tell you is that there are some things we are "just going to keep watching," as the doctors say.

One of those things is Aaron's chimerism. (P.S., I am going to do my best to give an accurate explanation of medical terminology and data, but please be patient with my limited vocabulary and expertise.)

A chimerism, you might remember, is when a person has two sets of DNA in their body. Ever since his bone marrow transplant, Aaron has had both his own DNA and Maxwell's. About once a month, he gets a blood draw to check the ratio of Maxwell's DNA to his own.

The cells that his doctors are most interested in are the T-cells (one of the types of white blood cells). It was Aaron's T-cells that attacked his bone marrow and caused the problem in the first place, and we really don't want them to do that again.

Right now, Aaron has a mixture of his and Maxwell's T-cells in his blood. For the past several months, we've been tracking those T-cells with increasing interest. When they were first measured in October, the T-cells were 47% Maxwell's and 53% Aaron's. When they were measured in December, we were all happy to find out that Maxwell's cells had increased to 75%. But the next month, they unfortunately dropped back down to 66%.

Before I could panic too much, Aaron's doctor assured me of a few things:

  1. One lower value does not actually reveal anything. In fact, if the numbers were plotted on a graph, they would still indicate an upward trend. Without more data, it is best not to draw any premature conclusions. (And incidentally, when Aaron's chimerism was checked this month, Maxwell's T-cells were at 69%, so even though it wasn't a significant gain, at least it didn't drop again.)
  2. The T-cells are just one small component of bone marrow. And at this point, all of the other blood cells are 100% Maxwell's. To put that into perspective, even though the T-cells are only 69% Max's, when all of the other cells are accounted for, Aaron's bone marrow is now something like 95% Maxwell's, which is pretty darn close to 100%. (It's just that the T-cells are the most critical to Aaron's full recovery so that is why they get more than their fair share of attention.)
  3. The anti-rejection drug that Aaron is still on suppresses the T-cells. It's critical to suppress those cells so that Aaron's bone marrow has a chance to heal without his own cells attacking Maxwell's or vice versa. So we really can't get a clear interpretation of what's happening until he comes off of that medication and his immune system fully wakes back up. (They will begin the weaning process next month.)
  4. It is common for the T-cells in bone marrow transplant patients to never reach 100% donor. As long as the two different DNA's play nicely together, it really doesn't matter if there are still a few of Aaron's cells in the mix. In fact, our doctor said that having both DNA's can actually help protect against GVHD (Graft Versus Host Disease) in the future. 
So that is why we have to just watch and wait right now: we can't do anything until we know more, and we can't know more until more time has passed.

The other thing we're watching is Aaron's cellular activity. When he was originally diagnosed, his cellular activity was less than 5%. Although it is normal for cellular activity to decrease with age, our doctor said that typical cellularity for an 11-year-old is about 80%. 

I was excited to find out what Aaron's cell activity is like now since it is obvious he is maintaining pretty consistent numbers (even if some of them are not in the normal range yet). When he got his central line removed last month, his doctor did a bone marrow biopsy to determine this.

The results were . . . disappointing. His cell activity came back at 20%, which seemed low to me. Dr. Boyer said at 100 days post transplant, they see that percentage anywhere from 10 to 50. So Aaron's results are not abnormal, but Dr. Boyer did admit that he's "on the low end." Knowing only a few other individuals with aplastic anemia, I have very little to compare to, but the ones I know all had a higher cellularity at this point, which makes it feel like Aaron is behind even if he is not. 

So that is why, even though Aaron's counts are looking good (they really are!), I feel like I have to keep the worst case scenario somewhere at the back of my mind. (I admit, this might not be the best idea for my mental health, but I can't seem to help myself.)

And what is the "worst case scenario," you ask? Well, that's the good news. 

If this bone marrow transplant doesn't end up working, then Aaron will have to do it again.

How could that possibly be good news? Because he gets a second chance (or even a third or fourth chance if necessary). This isn't cancer. A failed attempt does not mean some foreign cells are slowly taking over his body. Rather, his bone marrow just didn't figure things out on the first try and needs another pass at it. 

Of course, it would mean starting the process completely over, and that would really stink. Like, really truly. But we have a donor (although I shudder to think what said donor would do if we told him we needed his bone marrow once again), and we could do it.

But really, I'm getting ahead of myself. Even with the less-than-perfect numbers, all indicators still point to a full and complete recovery. 

And in the words of Dr. Boyer, "I can promise you we'll get this right. There's a slight chance we might have to do again, but in the end, we will get it. No question about it."

I'm banking on that and looking to the future with an eye of faith and hope. We have seen many miracles so far and trust that Aaron's healing will continue to go smoothly. Please continue to keep him in your prayers. 


  1. We are still thinking about you guys and praying for you!

  2. We continue to pray for sweet Aaron and the rest of your family. I hope those numbers continue to hold steady and shoot up to the needed levels when the time is right. Love you guys!

  3. I'm just getting caught up on reading your blog since I haven't been able to pop in for a while. Big hugs and well wishes for all of you. <3


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