@patwerthman my apologies if my reply confused you. Here is an excerpt from a published review article: "Bone turnover includes two processes: resorption (removal of old bone) and formation (laying down of new bone). N-terminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX-I) are markers of bone formation and resorption, respectively, that the International Osteoporosis Foundation and the International Federation of Clinical Chemistry recommend for clinical use. Bone turnover markere (BTM) may help to assess the response to anabolic and antiresorptive therapies, to assess compliance to the treatment, or to indicate possible secondary causes of osteoporosis." Hope this helps.

Not all endos use BTM during therapy although bone markers could be very useful at certain treatment juctures. In my case, they turn out to be very useful in monitoring treatment progress and in determining estrogen dosage. My treatment plan is set now for the foreseeable future unless my bone markers and/or annual dexa scan indicate otherwise.