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C-Telopeptide (CTX), Blood — Concentration

Published: August 9, 2026Updated: August 16, 2026

A blood test that measures C-telopeptide, a marker released when bone is broken down and used to assess bone turnover.

Quick summary

["Elevated C-telopeptide may indicate increased bone breakdown and should be interpreted with other bone-health findings."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
69103-0
Short code
CT Elbow-L W contr IS
Synonyms
CT Elbow-L W contr IS
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

C-telopeptide, also called CTX, is a small protein fragment released into the blood when bone tissue is broken down. Measuring its concentration provides information about the rate of bone resorption.

Why might I need this test?

This test may be used to assess bone turnover in people with osteoporosis or other bone conditions, monitor the effects of bone-loss treatment, or help evaluate a change in bone health. It is often interpreted alongside bone-formation markers and imaging.

How is the test performed?

A blood sample is collected, and the laboratory measures the concentration of C-telopeptide, typically using an immunoassay. The laboratory may process the sample as serum or plasma.

How do I prepare for the test?

No special preparation is usually required, but follow the laboratory's instructions. Because bone markers can vary with exercise, meals, and the time of day, the provider may request that the test be performed at a specific time.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A higher-than-expected C-telopeptide result can indicate that bone is being broken down faster than usual, as may occur with postmenopausal bone loss, osteoporosis, or some bone disorders. Lower results are less commonly used for assessment. Results should be interpreted by a clinician because CTX alone does not diagnose a specific bone condition.

Short name

C-Telopeptide (CTX)

Frequently asked questions

What does C-telopeptide measure?
It measures a protein fragment released into the blood as bone tissue is broken down. The result reflects the rate of bone resorption at the time of the blood draw.
Is a high C-telopeptide result proof of osteoporosis?
No. A high result shows increased bone breakdown but does not establish osteoporosis by itself. Your clinician will consider symptoms, other laboratory results, bone-density testing, and medical history.
Can this test monitor bone-loss treatment?
It may be used alongside other markers to monitor changes in bone turnover. A change in CTX during treatment can provide information, but it is not the only measure used to judge treatment success.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy