What was Your P1NP Increase on Tymlos at 1 Month?

@mayblin Thank you so much for this clarification -- for the article (a deep dive!) and the graphs. So if I understand correctly, P1NP is guaranteed to follow CTX down when resorption is blocked with a bisphosphonate. Hence, no need to get P1NP tested going forward. (And no need for any ratio.). You mentioned that a CTX number in the lower half of the range for healthy premenopausal women is the goal. Is that range 100-600 pg/ml? May I ask how you used this to figure out the right dosing for your HRT? eg, Did you test every six months and increase or decrease the dose depending on where you were in that range?

@kathleenrmt My doctor was not interested in ordering the BTM tests, even though I requested them. But her disinterest may have been related to insurance. Using my pick-your-battles mindset, once someone else on this site pointed out the low cost tests from Jason Health, I decided to get my own tests.

The question for the doctors & insurance companies tends to be on how test outcomes would guide treatment. I started HRT in October and deeply thank my doctor for immediately prescribing it and starting me on the most likely dose of 0.05 mg patches. I have seen stories on here about women struggling to find a doctor willing to prescribe HRT, and doctor putting the person on a tiny micro-dose. I want to check if my 0.05 HRT + other interventions appear to be working long before my next DEXA/DXA scan.

@kfhoz, i'd be interested in seeing your btm results when you get them, if you're open to sharing. We can compare notes - i'm on 25mcg transdermal estradiol patches.

@sebutler that's my thought exactly.

Depending on the lab one uses, the reference ranges can vary. For example, Quest lists 60–650 pg/ml for ages 30-39yo and 50–465 for ages 40-49yo. Based on those, the lower half starts roughly between 230 and 325 pg/ml. Coincidentally, many experts look for a CTX in the low 200s (or lower) when monitoring patients coming off Prolia to ensure bone is protected, or bone turnover is suppressed.

Please share your endo's CTX target when you get that info.

My original plan for HRT was to start with a low dose of 25mcg estradiol transdermal patch and gradually titrating up to 50mcg - the "standard" dose. Since there isn't a mountain of published data for every scenario, I had labs at 1, 3, and 6mo. Coming off Forteo, my starting "baseline" CTX/P1NP was 793/137, and here is how my CTX responded to just the low 25mcg dose: 572 (1mo), 302 (3mo), 163 (6mo), eventually settled in the low 100s after 9mo. My endos were very supportive of the data-backed decision. Worth noting, i also observed the coupling lag in P1NP. Having a highish P1NP at the start of HRT gave me a bit more confidence to titrate slowly (ended up staying at low dose).

@mayblin Once again, thank you for sharing all this info. So helpful. I know that Tymlos (and so Forteo, too) raises both P1NP and CTX, so stopping it would naturally bring them both down -- though, somewhere along the line I saw some data showing that it takes a few months at least for the CTX to decrease. Then, I guess, the HRT helped the process along and took over.

My gut always tells me that I want the P1NP to be higher, but I know the bone-remodeling process is tightly coupled between buildup and breakdown -- and hence that coupling between CTX and P1NP.

I will certainly share my endo's CTX target once I get it, but I won't be seeing her until November.

@mayblin Once again, thank you for sharing all this info. So helpful. I know that Tymlos (and so Forteo, too) raises both P1NP and CTX, so stopping it would naturally bring them both down -- though, somewhere along the line I saw some data showing that it takes a few months at least for the CTX to decrease. Then, I guess, the HRT helped the process along and took over.

My gut always tells me that I want the P1NP to be higher, but I know the bone-remodeling process is tightly coupled between buildup and breakdown -- and hence that coupling between CTX and P1NP.

I will certainly share my endo's CTX target once I get it, but I won't be seeing her until November.