@255anny, I agree with the comments that your CTX result was expected while on a strong bisphosphonate like Reclast. At this level bone remodeling (breaking down as well as new bone formation) is minimal and therefore your bmd is maintained.

When bone remodeling is strongly suppressed by bisphosphonates over a sustained period of time, it is harder for an anabolic such as forteo or tymlos to function 100% as these drugs build new bones requiring both osteoclasts’ and osteoblasts’ activities.

Evenity doesn’t rely on remodeling. However, its effect is also affected by prior use of a bisphosphonate. Here is a publication showing that with prior use of alendronate:
https://pmc.ncbi.nlm.nih.gov/articles/PMC9106644/
This article also provided how bone markers behaved in term of % changes from baseline.

The question for your endo could be, what’s an appropriate level of CTX for evenity to function after a person is treated with a bisphosphonate as strong as Reclast? 100s? 200s? 300s? Or does it matter? I couldn’t find any literature with that information. If the answer is known, then you could monitor CTX to time the start of second round of evenity; or possibly, no timing is needed.

To me, it’s ideal to get bone markers tested when you are venturing with some uncommon route so that you know how you respond to a particular therapy. I believe some of us will cycle anabolic - antiresorptive back and forth several times from now on, instead of using a maintenance antiresorptive for the rest of our lives. It’s imperative to know what worked and what didn’t, and maybe the ‘why’. I understand the drawbacks of bone marker testing. But getting some information is better than no information.

It is worth getting both CTX and P1NP tested at least once before your second round of evenity as a new ‘baseline’.