P1NP and CTX results

I have had 3 sets of bone marker tests at Quest. The most recent one was May 29th. I asked to have the results sent to two doctors, not to have the same test repeated twice and not to be charged twice. Wouldn't you know, two tests were done twice, the comprehensive metabolic panel and P1NP. None of the results on the two tests are the same, even though it was the same blood draw. Calcium was 9.3 for one doctor and 9.7 for the other. P1NP was 179 for one doctor and 203 for the other. I'm wondering how reliable blood tests are!

Following are my bone marker results:

Date P1NP CTX Ratio
12/23 78 519 One month 20mcg Tymlos 15.02
5/24 190 1401 3 months 40mcg Tymlos 13.56
8/24 310 1414 6 months 40mcg Tymlos 21.92
12/24 190 1238 3 weeks 20mcg Forteo 15.34
4/25 179 or 203 912 5 months 20mcg Forteo 19.63 or
22.25

I know that my CTX is too high, but it is getting lower. Does anyone know if the markers indicate that Forteo is helping my bones? My recent REMS test showed that my small spine BMD improvement on Tymlos disappeared on Forteo. I also had marginally worse fragility and fracture risk on spine and hips than previously on Tymlos. In the last month, I have developed unpleasant side effects from Forteo. I am considering going back on half dose Tymlos.