Bone turnover markers (CTX and P1NP): do you have a baseline?

In this context patient should only be used as a noun. Patience isn't a virtue in the health care.
I lost my pen's mid care (they may have been stolen). After a month my CTX had dropped at a greater percentage than the P1NP to the advantage of my bones. I suspect a three week interruption would have been preferrable.

@gently could you clarify the timeline of your "After a month my CTX had dropped at a greater percentage than the P1NP to the advantage of my bones"? Were the readings one month after interruption or one month after restarting Forteo? CTX and P1NP both had a drop? Thanks

@gently

I am sorry your med was stolen! Despicable ! But I’m glad it ended up to your benefit! What a relief for me to know that—thank you! Your message is so well timed. I just finished my walk and with a clear mind was reflecting that this pause may be to my benefit. I had labs done yesterday, and although the bone markers are still pending, a lot of the rest is available for view. All is well except that my vitamin D has gone from being strongly in range, to below the acceptable range. Good to know and I will address it with doc when have all info in and can address all/any issues at once (very busy office so want to just address everything at once if possible). I firmly believe in taking responsibility and being assertive and getting things done (you are right—a thin line between being reasonably patient and becoming overlooked and falling between the cracks—pun intended haha!) and I also believe our Lord can and will work things out for our good! Excited to see how all this goes! Thank you, again, for helping me feel more sane about the med interruption!

@mayblin
647 pg/mL to 424pg/mL CTX
102 mcg/L to 126pg/mL P1NP
The only thing this proves is that you shouldn't try to discretely give yourself an injection in the airport, even if your flight is delayed.
Intriguing though.
Any thoughts?

It is indeed intriguing both CTX and P1NP trended in favor of bone building. I wonder if this phenomenon is repeatable, or if it is related to the stage of Forteo therapy. Thank you very much for sharing @gently !

hi mayblin, if it were repeatable would repeats obviate the significance of stage?
Many of the research articles use CTX and P1NP as direct indications that bones are strenghtening or at least gaining density. Is there a CTX/P1NP thread? It would be interesting to align bone markers with dxa results.

That's a great question @gently . I'm amazed with the fact that the original 2yr treatment limit for Forteo coincides with the anabolic window, which was reflected in CTX and P1NP changes in various studies. If the results of Fisher rats didn't exist, we'd have a lot more info about teriparatide's longer term efficacy, maybe a lot more about dosing regimen as well. Moreover, we might not have the current situation where long term op management is heavily dependent on antiresorptives while the other side of equation is partially missing.

This has been such an educational thread!

My bone markers
Last June 2024 (after being diagnosed with osteoporosis but no meds or hormones)
CTX = 393
P1NP = 72
drawn at 9am on the same day fasting. My regular sleeping schedule is 1am-8am.

While wrestling with insurance to get approval for Tymlos or Forteo, I started HRT. My E2 numbers are still abysmal (another story) - let's just say I am well below the 60 pg/ml they recommend for bone protection

My March 2025 bone markers
CTX = 331
P1NP = 45
drawn at 9:30am, fasting - but over two days (on Day 1 they hemolyzed the CTX sample so I came in the next day for a CTX redo. Same time, also fasting) My regular sleeping schedule is 1am-8am.

It is hard for me to decide if things are getting better or worse using the various formulas I am seeing here.

Since I am doing nothing right now (the HRT is below the therapeutic dose), the 38% reduction in bone building (P1nP ) is not matched by the 18% reduction in CTK (bone breakdown). If they matched in percentage decrease, I'd say I am holding my own, just at a slower speed. But my P1nP was very high in June 2024 - without being on any meds or hormones, so I don't know what that means,

If I was on a bisphosphonate which pushes down both CTX and P1nP - I'd say I would be doing worse, as my CTX went down 18% but my P1nP went down 38% I may be breaking bones less but I am not keeping up with rebuilding them

And if I was on a bone builder like Tymlos I'd say my results are definitely worse because everything is less.

Thoughts welcomed.

Hi @casstk thank you very much for sharing!

There were studies done on the circadian variations in serum CTX. According to one publication, CTX peaked in early morning hours (~5am) and reached a trough around 14:00 in the afternoon. It was not affected by 5 days of bed-rest, by absence of a normal diurnal variation in cortisol production, or by absence of a normal light cycle (blindness). Peak and trough differed in the magnitude of 80% on average.

Your 2024 baseline ctx and p1np were nice, especially with p1np at 72. However if the above observation applies, then your baseline ctx reading probably would turn out to be higher if your blood draw was earlier, say at 8am regardless of your sleeping pattern/schedule. I don't know what other members think, but I felt blood draw at 9:30am is considered late. This being said, it is important to get blood draw at consistent time for proper comparison,

How Long have you been on HRT? What dose and form of estradiol you are using? Are you on testosterone?

The relationship between serum estradiol level and bone effects (specifically on ctx) puzzles me. With a low dose 0.025mg/day transdermal E2 patch, my blood estradiol level moved only a few points to 21 from baseline 18. However, my ctx went down to 163 from 793 at end of forteo treatment. Of course discontinuing forteo had effects on ctx but still, that's a whopping change.

When your tymlos/forteo gets approval, are you planning to use it alone or with HRT as a combination? I'm very interested in hearing this aspect of planning from you. And, please share when your corrected CTX lab result is available if you could. Thank you!

my thoughts is do more research and you will find out why these markers have to be taken with a grain of salt in the short haul. My specialist only did it because I complained and wanted baselines. Then I read the research, and it is indeed unreliable by themselves. It is just a tool from year to year. Looked at over a few years. You didn't say the break between your testing.
Do a DEXA WITH A TBS SCORE a year apart and see how that looks. I can tell you my regular DEXAS were okay over 20 years with the last one saying I had come out of ostopenia even! Then I had cervical surgery and my C5 fell apart in their hands! I asked the surgeon how it could be and he explained they are standardized tests, and as well, your body bones have different density requirements. Nobody ever did a DEXA on my neck! So don't worry!