You are still a relatively new transplant. It is not unusual for Prograf levels to fluctuate a lot early on. That is why you have blood test fairly frequently. I imagine you are having them at least once per week, no? After about 5 months post TP, the prograf level should be more stable, and is desireable to be at 3 to 8. I wouldn't worry about the numbers you have, just talk to the Dr. with any concerns.
Prograf levels can fluctuate. Going from13.6 to 6.5 is a greater fluctuation than I generally see with my labs but I have seen a 3 point difference and I am 8 years out.. I believe that diarrhea can cause an elevation in Prograf level. Taking Prograf with food can decrease absorption and result in a lower Prograf level. This is even more pronounced if you take it with fatty food. If Prograf doesn't upset your stomach it is best taken about 1 hour before eating - on an empty stomach.
The range on my labs sheet is 4 - 16 so you are well within range. This early post transplant I wouldn't worry too much about a fluctuation unless it was downward and below the reference range. My guess is that you will settle down to around 6 or 7. Of course, lab error is always a possibility which can't be ruled out. Basically, I think your number are nothing to worry about. And, if you are, ask someone on your transplant team - probably your coordinator would be the place to start.
I wish you good luck,
Mike
Sorry I don't know anything about a transplant. Hope I never do. I'm glad you are doing well with yours. There is a Transplant Forum here. I think you would get a lot of feedback from them.
There's also a forum to ask a Dr. a question. Check it out.