What is the Collagen Type 1 Cross-Linked N-Telopeptide (NTX) test?

The Collagen Type 1 Cross-Linked N-Telopeptide (NTX) test measures fragments of type I collagen released into the blood or urine when bone is broken down. Type I collagen is the main structural protein in bone, and NTX reflects active bone resorption.

When bone breakdown increases, NTX levels rise. This makes NTX a sensitive biochemical marker of skeletal turnover, providing real-time information about bone metabolism rather than bone density alone.

NTX testing is commonly used in the assessment of osteoporosis, metabolic bone disorders, and to monitor the effectiveness of treatments that aim to reduce bone loss.

Why do I need an NTX test?

Bone loss often progresses silently until fractures occur. NTX testing helps identify excessive bone breakdown early and supports monitoring of treatment response.

It is particularly useful alongside bone density scans, as it shows how quickly bone is being lost, not just how dense it is.

You may need an NTX test if you:

• Have osteoporosis or osteopenia
• Are postmenopausal
• Have a history of fractures
• Are taking steroid medication
• Have thyroid or parathyroid disorders
• Have suspected metabolic bone disease
• Are starting or monitoring osteoporosis treatment
• Have unexplained bone pain or fracture risk

Benefits of the NTX test

·      Measures active bone resorption
Reflects real-time bone breakdown.

·      Supports osteoporosis assessment
Complements bone density testing.

·      Monitors treatment effectiveness
Shows response within months.

·      Identifies early bone metabolism changes
Detects risk before fractures occur.

·      Supports fracture risk evaluation
Higher levels are linked to increased risk.

·      Clinically recognised bone marker
Used in metabolic bone disease assessment.

·      Useful in hormonal bone changes
Relevant in menopause and endocrine disorders.

·      Simple laboratory test
Requires a blood or urine sample, depending on method.

Step by step – how the test works

You can access NTX testing UK-wide through two options:

1.    Clinic appointment
Attend your nearest UK clinic, where a healthcare professional will collect the required sample.

2.    At-home or hotel visit (£60 extra)
A qualified phlebotomist visits your home or hotel, so you don’t need to travel.

Your sample is analysed in an accredited UK laboratory, and results are delivered securely.

Your results explained

Low NTX levels

Suggest low bone turnover, often seen with effective osteoporosis treatment or reduced bone resorption.

Typical UK interpretation:

• Below laboratory reference range

Normal NTX levels

Indicate balanced bone remodelling with normal rates of bone breakdown.

Typical UK interpretation:

• Within laboratory reference range

High NTX levels

Indicate increased bone resorption. This may occur in osteoporosis, menopause, hyperthyroidism, or untreated metabolic bone disease.

Typical UK interpretation:

• Above laboratory reference range

Reference ranges vary depending on laboratory methodology and sample type.