@manutebol -- Thanks for your reply! I really do appreciate it. I did discuss this topic with my visits with the Mayo staff urologists at 3 month and 6 month checkups. A couple of points are (I believe) key here: first, Mayo didn't specify the machine. They just gave me an order for a standard psa test. My local lab happened to run it on 2 different machines which provided the difference in both results. But in both cases, the psa was at the bottom of each machines respective calibration scale. So I don't think there's really any significance to the differences. Second, both staff urologists I saw were quite definitive that staying below .2 is the goal and there really isn't anything to do unless and until that number is reached. Speaking only for myself, I'm very comfortable following their guidance since Mayo is a CCOE and I've received outstanding care from them so far. I do understand your comment regarding ".099" and I think it's a thoughtful and precise analysis. But in this case I'm also relying on the experience of my Mayo care team to help balance between what I'd characterize as overthinking the numbers (which I'm prone to do) versus prudent care. Could I be wrong and it bite me in the ass; yes it could. But I'm not ignoring it and I will be getting another psa test in 3 months as scheduled. For now I think that's enough, but more importantly my care team at Mayo thinks that's enough. All that said, thanks again for your response and I really do appreciate it.