C-terminal telopeptide

Overview

The C-terminal telopeptide (CTX) is a biomarker used in the assessment of bone resorption. It is a fragment of type I collagen, which is the most abundant collagen in the human body and a major component of the bone matrix. CTX is released into the bloodstream during the process of bone degradation by osteoclasts.

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Diagram of C-terminal telopeptide

Structure and Function

Type I collagen is composed of three polypeptide chains that form a triple helix. The C-terminal telopeptide is a non-helical region at the end of the collagen molecule. During bone resorption, osteoclasts break down the bone matrix, releasing CTX into the circulation. The measurement of CTX levels in the blood or urine provides an indication of the rate of bone turnover.

Clinical Significance

CTX is commonly used in clinical practice to monitor bone health, particularly in conditions such as osteoporosis. Elevated levels of CTX indicate increased bone resorption, which can be a sign of bone loss. Monitoring CTX levels can help in assessing the effectiveness of treatments for osteoporosis and other metabolic bone diseases.

Measurement

CTX can be measured in both serum and urine samples. The serum CTX test is often preferred due to its convenience and the stability of the biomarker in blood. The test is typically performed using immunoassays, which are sensitive and specific for the detection of CTX.

Related Pages

• Osteoclast
• Osteoporosis
• Bone resorption
• Type I collagen