I asked for the CXT and P1NP blood tests when I started Tymlos. My endo prescribed the tests so that we can measure progress. My results were P1NP 78 and CTX 519. He thought that those were good results, but I'm sure that at least the 519 is way too high. I am still breaking bones. I recently developed a stress fracture on my forefoot, and I have broken 4 other bones in the last 2 years. I have another Dr appt in April and will ask for the tests again. I have been on 20 mcg of Tymlos for 3 months waiting for insurance approval. Now that it is finally approved, I have taken 37.5 mcg the last two nights. I plan to work up to 40 mcg. My endo was OK with only 20 mcg, but I think I should at least take a half a dose. I want to thank @windyshores for suggesting ramping up the dosage. Otherwise, I wouldn't be taking it at all, because I had horrible side effects from the full 80 mcg dose.