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

Posted by mayblin @mayblin, Mar 27 11:05am

Currently i am on forteo therapy with a couple bone markers tests done. However, I didnt have ctx or p1np tested before the start of forteo as a baseline, regrettably.

It is known that the CTX value varies greatly among different individuals, with a very wide range. For post menopausal women, the range could be 34 - 1037 pg/ml; while for perimenopausal women 34-635 pg/ml. Different labs also have a slight different range values.

CTX, a bone resorption (breakdown) marker, is heavily influenced by a number of factors, such as food intake, circadian variation and exercise/life style, etc.

Bone remodeling is a dynamic and complex process. CTX itself may not fully reveal the whole picture. The bone building marker P1NP, is a lot less influenced by external factors. Taking both into consideration at the same time may shed more lights than looking at CTX or P1NP alone.

For those who had their CTX and P1NP tested before treatment with a bone drug, could you share the results if you don't mind? Thanks a lot!

Interested in more discussions like this? Go to the Osteoporosis & Bone Health Support Group.

esb13 | @esb13 | Jul 3 9:28am

In reply to @melia7 "Thank you so much for your help." + (show)

To all on this thread - is a baseline p1np of 82 okay? I’ve been on Tymlos for 1 1/2 months now and will test this again at 3 months. Interestingly, my calcium dropped a bit from a preTymlos level of 10 to 9.4 after a month on Tymlos. We will test again after 2 months. I think I was so concerned about high calcium, I intentionally stopped my high calcium food regimen. Also - has anyone ever heard of possibility of Tymols not impacting OP with better DEXA?
Thank you everyone!

esb13 | @esb13 | Jul 3 11:43am

In reply to @hopefullibrarian "babbsjoy, You're not on any osteo meds? Have you ever taken any? I ask, because your..." + (show)

I am not sure how to do this math :). With a CTX of 144 and a P1np of 82, what is the ratio? Although the CTX was taken a year ago and the P1NP was the day before Tymlos treatment a month ago. My Endo believes the CTX is not reliable and to instead follow the P1NP numbers over the course of treatment. But I am intrigued by this conversation and interested in the ratio if anyone can help. Thank you!

hopefullibrarian | @hopefullibrarian | Jul 3 8:22pm

In reply to @esb13 "I am not sure how to do this math :). With a CTX of 144 and..." + (show)

Hi esb13,

Both the CTx and the P1NP tests need to be conducted simultaneously for their ratio to provide meaningful information. This ratio provides a snapshot in time and is crucial for accurate assessment.

I'm not at all surprised that your Endo believes the CTx is unreliable. CTx is particularly sensitive to certain factors. It will only give useful results if done correctly. For optimal accuracy, it's essential not to take collagen or biotin supplements for 48 hours prior to the test. Additionally, fasting overnight and scheduling the test first thing in the morning (preferably before 8:30 am) are recommended. Ensuring consistency in the timing of each test is also important.

Your Endo also said to just follow the P1NP numbers. It's true that if this number goes up, as it should on Tymlos, you're more likely than not growing bone, or at least slowing down loss. Some people, for whatever reason don't respond well to treatment. In some cases, their CTx may still be very high. I prefer to have as much data as possible to track my treatment success. Knowing both the CTx and the P1NP, I can calculate the bone turnover ratio, and that's reassuring for me.

I'll put the equation I use, and a sample calculation to find the 10 to 1 ratio below. If you choose to have both tests done together in the future, I hope you'll find it useful.

Using the values from @babbsjoy's earlier input:
CTx = 231
P1NP = 41

The equation for the ratio is CTx/P1NP = 10/x.

Sample calculation:
231/41 = 10/x
10 ÷ (231/41) = x
10/5.63 = 1.77
x = 1.77

I hope that Tymlos works well for you. If my numbers weren't so bad, and I hadn't had a compression fracture, I would have opted for that before Evenity. Best of luck.

esb13 | @esb13 | Jul 3 8:53pm

In reply to @hopefullibrarian "Hi esb13, Both the CTx and the P1NP tests need to be conducted simultaneously for their..." + (show)

Thank you! It never occurred to me Tymlos might not work. Oy. Do you have data on percent of people who are no better off after two years of full dose nightly
Injections? I have had great hope this will be an effective treatment. I will try to stay positive for sure! Thank you.

hopefullibrarian | @hopefullibrarian | Jul 3 9:58pm

In reply to @esb13 "Thank you! It never occurred to me Tymlos might not work. Oy. Do you have data..." + (show)

I can't cite any studies or data on the number of people who find Tymlos doesn't work for them, or who have had underwhelming results. Based on what I've read from members of this support group who've shared their experience, it works well for almost everyone, though to varying degees. There's a thread started by @katwhisperer earlier this year that might be helpful for you.
https://connect.mayoclinic.org/discussion/disappointing-results-would-you-continue-or-skip-2nd-year-of-tymlos/
No matter what the number of people who don't respond to Tymlos treatment, it's good to track your progress to make sure you're not one of them.

hopefulheart | @hopefulheart | Jul 4 6:53am

In reply to @hopefullibrarian "babbsjoy, You're not on any osteo meds? Have you ever taken any? I ask, because your..." + (show)

Feeling stupid and I thought I was good at math
HOW do I figure out the 1 to 10 ratio?

My p1np is 37
CTX is 336
Not on any meds yet
Starting soon very likely

njhornung | @normahorn | Jul 4 7:43am

In reply to @hopefulheart "Feeling stupid and I thought I was good at math HOW do I figure out the..." + (show)

Keep it simple. Divide CTX by PINP. For you that number is 9.08 which is essentially equal to the "magic" 10:1 ratio. If you blindly accept these ratios, my value of 4.2 should mean I do not have osteoporosis but I do.