Marker for bone resorption

Marker for bone resorption

• A. Cross-linked C telopeptide
• B. Osteocalcin
• C. Alkaline phosphatase
• D. Parathyroid hormone

Answer: (A)

Cross-linked C telopeptide is a marker of bone resorption because it is a fragment released when type I collagen is degraded during osteoclast-driven bone breakdown. As bone is resorbed, collagen is cleaved and these cross-linked peptides enter the bloodstream and urine; measuring CTX gives a direct readout of how much bone is being resorbed. In contrast, osteocalcin is produced by osteoblasts during bone formation, and alkaline phosphatase reflects osteoblast activity rather than resorption. Parathyroid hormone regulates calcium balance and remodeling more broadly but is not a direct marker of bone resorption.

Cross-linked C telopeptide is a marker of bone resorption because it is a fragment released when type I collagen is degraded during osteoclast-driven bone breakdown. As bone is resorbed, collagen is cleaved and these cross-linked peptides enter the bloodstream and urine; measuring CTX gives a direct readout of how much bone is being resorbed.

In contrast, osteocalcin is produced by osteoblasts during bone formation, and alkaline phosphatase reflects osteoblast activity rather than resorption. Parathyroid hormone regulates calcium balance and remodeling more broadly but is not a direct marker of bone resorption.