1. < Osteoporosis & Bone Health

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!

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mayblin | @mayblin | 3 days ago
In reply to @normahorn "Keep it simple. Divide CTX by PINP. For you that number is 9.08 which is essentially..." + (show)
@normahorn

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.

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@normahorn your btms are puzzling to say the least. One thought, if you have the luxury of time before any treatments, repeat dexa yearly to get a feel for annual rate of bone loss. Personally I'd repeat btms in 6 months just to see any possible variation.

Has your endo done exhaustive exams or tests to exclude secondary causes (at this point I'm sure you went thru lots of testing)? Did you in the past (or present) have meds or disease states that would adversely affect bone health? Things happened in the past could've affected bone density but the factor(s) may no longer be present, such as calcium intake/diet, sedentary life style, a particular rx or disease state.

Even everything appears to be good, our bones go downhill as we age, just with a different speed for each person. A person I know who has been conscious with health throughout her life, had her btms and dexa followed for years. Her btms looking good, dexa "deteriotes" at a normal speed as a postmenopausal woman. Now in her mid 70s, she has op according to criteria of T score.

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melia7 | @melia7 | 3 days ago
In reply to @mayblin "@melia7 your CTX is in mcg/L, that is, micrograms per liter. To convert to pg/ml (picograms/ml,..." + (show)
@mayblin

@melia7 your CTX is in mcg/L, that is, micrograms per liter. To convert to pg/ml (picograms/ml, the units used here in the US), you multiply 1,000,000 then divide it by 1000:
(0.57 x 1,000,000)/1,000 = 570 pg/ml, just like @normahorn said to multiply your lab value by 1000; as 1 mcg = 1,000,000 pg and 1 Liter = 1,000ml.

Your P1NP has the same unit as used here in US mcg/L.

What's your frax score if you don't mind sharing? Will risedronate be your first bone med? What's the plan of length using risedronate?

I don't have a baseline bone markers unforturnately, although I had P1NP tested at 13 month of FORTEO which showed a tremendous boost (400). Later the bone markers were monitored periodically and they are trending nicely.

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to @mayblin
About frax score:

I have 4,9 for spine and 1,3 for hip.
The risedronate will be the first medicine, and Dr. said if the results will be OK, I can stop it in 3-4 years. It all depends on many factors.

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1 reply
hopefulheart | @hopefulheart | 3 days ago
In reply to @normahorn "Keep it simple. Divide CTX by PINP. For you that number is 9.08 which is essentially..." + (show)
@normahorn

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.

Jump to this post

Thanks
But confused since mine is 9.08 and I’m close to 10
How would your 4.2 seem like you don’t have osteoporosis but do ?

Shouldn’t we be close to 10?

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nme1985 | @nme1985 | 3 days ago

Can you clarify I don’t understand the numbers?

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njhornung | @normahorn | 3 days ago
In reply to @hopefulheart "Thanks But confused since mine is 9.08 and I’m close to 10 How would your 4.2..." + (show)
@hopefulheart

Thanks
But confused since mine is 9.08 and I’m close to 10
How would your 4.2 seem like you don’t have osteoporosis but do ?

Shouldn’t we be close to 10?

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As I understand it, the larger the number is means that one is losing bone faster than building new bone. Conversely, the smaller the number, bone building is occurring at a faster rate than bone loss is. However, that is a far too simplistic approach but makes people feel that they have some control.

The value would come in monitoring changes during treatment.

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1 reply
hopefullibrarian | @hopefullibrarian | 3 days ago
In reply to @hopefulheart "Feeling stupid and I thought I was good at math HOW do I figure out the..." + (show)
@hopefulheart

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

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Don't feel bad. It took me a long time to remember how to calculate ratios. I was really frustrated. Thankfully, Google was a big help.

Based on your CTx of 336 and P1NP of 37, your ratio is 10:1.1. This is a great ratio for maintaining bone health. Many factors influence bone turnover, so it's hard to say why your numbers were good on that particular day. Considering you have osteoporosis, this hasn't always been the case. It could have been a one-time thing, so take these numbers as just a snapshot

Here's the calculation
CTx/P1NP = 10/x.
336/37 = 10/x
10 ÷ (336/37) = x
10/9.08 = 1.1
x = 1.1
Resulting ration 10 : 1.1

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1 reply
hopefulheart | @hopefulheart | 3 days ago
In reply to @hopefullibrarian "Don't feel bad. It took me a long time to remember how to calculate ratios. I..." + (show)
@hopefullibrarian

Don't feel bad. It took me a long time to remember how to calculate ratios. I was really frustrated. Thankfully, Google was a big help.

Based on your CTx of 336 and P1NP of 37, your ratio is 10:1.1. This is a great ratio for maintaining bone health. Many factors influence bone turnover, so it's hard to say why your numbers were good on that particular day. Considering you have osteoporosis, this hasn't always been the case. It could have been a one-time thing, so take these numbers as just a snapshot

Here's the calculation
CTx/P1NP = 10/x.
336/37 = 10/x
10 ÷ (336/37) = x
10/9.08 = 1.1
x = 1.1
Resulting ration 10 : 1.1

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Thank you !

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babbsjoy | @babbsjoy | 3 days ago
In reply to @hopefullibrarian "Hi esb13, Both the CTx and the P1NP tests need to be conducted simultaneously for their..." + (show)
@hopefullibrarian

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.

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@hopefullibrarian,
Thank you for doing this calculation, and for the formula for us all to use!

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hopefullibrarian | @hopefullibrarian | 3 days ago

I apologize if my previous explanations about CTx to P1NP (CTx:P1NP) were unclear. Let me attempt to clarify here. But before I do, I'd like to share a simpler way to track treatment progress that I learned from a YouTube video from Dr. Doug Lucas posted last December.
You can watch it here: https://youtu.be/NgZf1Vu8UyM?si=elj8Y6u_bWMLY9UT

Dr. Lucas uses this equation:
P1NP ÷ (CTx ÷ 1000) = X

When the result (X) increases, it indicates you're moving in the right direction. Here are my results from January and April using this calculation:

- Before Evenity treatment (January): X = 95.5
- 2 weeks after the 3rd Evenity treatment (April): X = 287

The number went up dramatically with Evenity treatment, so I know that it's working.

Now, let me provide a clearer explanation of the 10:1 ratio:

A good ratio in this context means that for every unit increase in CTx (a marker of bone breakdown), we ideally want to see a proportional increase in P1NP (a marker of bone formation).

For instance, if the ratio is 10:1 (10 to 1), it suggests that for every 10 units of CTx, there is 1 unit of P1NP. This indicates a balance where some bone formation is occurring relative to bone breakdown.

If our goal is to increase P1NP, we should ideally see the ratio adjust accordingly. A higher ratio, like 10:2 or 10:3, would mean that for every 10 units of CTx, there are 2 or 3 units of P1NP, respectively. This higher ratio indicates more bone formation relative to bone breakdown, which is beneficial for bone health.

Therefore, a good ratio when aiming for an increase in P1NP shows a proportional or higher increase in P1NP compared to CTx, suggesting improved bone formation relative to breakdown."

I hope that's helpful. It can be a real brain twister.
If your goal is just to track treatment progress, I recommend using Dr. Doug's equation. It's far more straight-forward.

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1 reply
hopefullibrarian | @hopefullibrarian | 3 days ago
In reply to @normahorn "As I understand it, the larger the number is means that one is losing bone faster..." + (show)
@normahorn

As I understand it, the larger the number is means that one is losing bone faster than building new bone. Conversely, the smaller the number, bone building is occurring at a faster rate than bone loss is. However, that is a far too simplistic approach but makes people feel that they have some control.

The value would come in monitoring changes during treatment.

Jump to this post

Hi normahorn,
I attempted to write a clearer explanation of how the ratio can be useful in a separate comment. You can jump to it here: https://connect.mayoclinic.org/comment/1099229/

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