Understanding CTx and P1NP - Key Bone Markers






C-terminal cross-linked telopeptide (CTx) and procollagen type 1 N-terminal propeptide (P1NP) are key bone turnover markers in managing Osteoporosis. Below I have identified what they are and how they are used.

CTx, short for C-terminal telopeptide, is a biochemical marker used to assess bone resorption, the process by which bone is broken down and minerals are released into the bloodstream. Specifically, CTx measures fragments of type I collagen, which is a major protein found in bone. When bone is resorbed, these fragments are released into the blood and can be detected as an indicator of bone turnover.
Generally, a baseline CTx measurement is taken before treatment, and follow-up measurements are done to monitor changes and adjust treatment if necessary.
The best time to perform a CTx test is typically in the morning, while fasting. CTx levels can fluctuate throughout the day and are influenced by food intake, so fasting overnight and testing early in the morning helps ensure consistent and reliable results.
Following these guidelines ensures reliable CTx results, providing a clearer understanding of bone health and treatment effectiveness.
Additionally, P1NP (Procollagen Type 1 N-Terminal Propeptide) is a key marker of bone formation. It reflects the activity of osteoblasts—cells responsible for creating new bone. When new collagen (type I) is formed, P1NP is released into the bloodstream, making it a valuable indicator of the bone formation rate.
P1NP testing does not require fasting and can generally be done at any time of the day. Unlike CTx, P1NP levels do not have significant diurnal variation, making it a more flexible test in terms of timing.
I typically get both tests done together.
This flexibility allows healthcare providers to monitor bone formation without the strict timing constraints required for CTx.
👉 Like CTx, P1NP is often measured before starting treatment and then periodically to track changes, allowing for adjustments to treatment plans based on bone health needs.
These tests validate the effectiveness of strategies aimed at improving bone health and preventing fractures.
Hello friends of bones:
I’m happy to present my Bone Turnover Marker PDF from my interview with Dr. McCormick.
We discussed:
What are Bone Markers?
Why are they necessary?
What is the best way to get an effective test?
My gift to my community is the easy-to-navigate clickable transcript.
(more…)Hello friends of bones:
I’m happy to present my bone supplement interview with Dr. McCormick. We discussed his full line of bone supplements which are an important ingredient for healthy bones and why calcium in lower doses matters.
A number of attendees mentioned they were not able to get into the zoom call.
My 2022 gift to my community is the recording and the transcript.
(more…)


