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.

nme1985 | @nme1985 | Apr 26 6:17pm

Sorry CTX

mayblin | @mayblin | Apr 26 7:57pm

In reply to @nme1985 "Sorry CTX" + (show)

Let’s wait till your CTX results come back and look at both P1NP and CTX together @nme1985.

nme1985 | @nme1985 | Apr 26 8:02pm

I am just so worried thank you all for the support.

bluebonnet242 | @bluebonnet242 | Apr 30 9:28am

@mayblin. How often do we test for CTX and P1NP. I read to test before starting meds but how often do we test once we have started the meds? Specifically for Tymlos please. Thanks!

bluebonnet242 | @bluebonnet242 | Apr 30 9:30am

@mayblin Any other recommended tests prior to starting Tymlos?

mayblin | @mayblin | Apr 30 1:51pm

In reply to @bluebonnet242 "@mayblin Any other recommended tests prior to starting Tymlos?" + (show)

Most likely your endo will do bunch of tests first to rule out some obvious secondary causes for op. Here is what I had:

The first set of blood work my endo ordered were:

Vit D
24hr urine calcium w/ creatinine
Parathyroid hormone
Celiac disease diagnostic panel
Basic metabolic panel
AM cortisol level
Dexamethasone challenge (1mg o/n), test 8-10am

Later we did:
Plasma histamine
Prolactin level
Serum electrophoresis
Tryptase
Magnesium level

During FORTEO we did:

Periodic Vit D check (~every 3-6mo) and metabolic panel

Monitor blood calcium @3mo, 6-9mo forteo: metabolic panel includes this

I didn’t have baseline btms, but started at one year and now doing every 3mo. Trending very nicely

After all the tests came back, we think I have op due to loss of estrogen.

Oh I think thyroid hormone t4 and tsh needs to be checked. if you had or having certain meds such as ssri, ppi, oral corticosteroids or ai etc, tell your doc. Other disease states like ibs also can be a cause. My doc took a detailed medical and family history. @windyshores had a long list of causes posted somewhere on this forum.

If I could locate the full list of dx labs for most causes for op, I’ll post it here.

bluebonnet242 | @bluebonnet242 | Apr 30 6:34pm

In reply to @mayblin "Most likely your endo will do bunch of tests first to rule out some obvious secondary..." + (show)

Thanks so much for sending this! I’m finally approved for Tymlos and had an appointment with rheumatologist. I asked about the tests and he mainly does calcium and dexa. He told me endocrinologists are more likely to do the CTX and P1NP and would not order them or any of the other tests mentioned. He said if I really wanted the tests he would refer me to an endo, was very nice about it but didn’t want to do the tests.

So, I’ll see if pcp will order them and will probably switch to an endo. I have an appointment set up with endo at Mayo the end of June.

@mayblin did you have the 24hr urine calcium test with creatinine because of high calcium or it was just a preliminary test you doctor would have ordered for most patients on an anabolic?

mayblin | @mayblin | Apr 30 8:33pm

In reply to @bluebonnet242 "Thanks so much for sending this! I’m finally approved for Tymlos and had an appointment with..." + (show)

🥂congrats on the tymlos approval!

24hr urine with creatinine mainly is to rule out secondary causes of op. There are ppl peeing out extra calcium then the body turns around to rob calcium from bones for essential body functions. This is important to rule out or anabolics are not going to build meaningful new bones. I’ll get back to your other qs later.

debsinwa | @debsinwa | May 2 9:31am

I started Forteo in October 2023. I did both P1NP and CTX tests before starting the drug and just did them again (6 months later) here are my results:
8/2023 4/2024
P1NP 45.9 ng/mL 220.3 ng/mL
CTX 444 ng/mL 1293 ng/mL

mayblin | @mayblin | May 2 9:32am

In reply to @bluebonnet242 "@mayblin. How often do we test for CTX and P1NP. I read to test before starting..." + (show)

A baseline P1NP and CTX for sure.

In a paper by Estell et al., results from ACTIVE showed early btms changes correlates to lumbar spine bmd changes at 18mo of abaloparatide (Tymlos). The initial P1NP increase is evident during 1-3mo. Trial data showed btms at 1,3,6,12 and 18mo. If your endo and insurance both offer tests, why not do them all? If you were to experience severe side effects and will need to ramp up dose as @windyshores described, likely you will get P1NP response at later months.

If your insurance only allows limited btm testing, and assuming you use max (80ug) or close to max dose at the beginning months, personally I’d chose 2 mo, 6 mo and 18mo (this one to determine if you want to continue use for a total of 24mo).