CTX-II (Carboxy-Terminal Telepeptides of Type II Collagen), Urine
Biological or Clinical Significance:
Bone is constantly undergoing a metabolic process called remodeling. This includes a degradation process, bone resorption, and a building process, bone formation. Crosslinked telopeptides collagens are the products in the remodeling process. While telopeptide of type I collagen accounts about 90% of the organic matrix of bone, the type II collagen is the major organic constituent of cartilage. Disruption of the structural integrity of cartilage is the major histological finding in osteoarthritis and rheumatoid arthritis. Following the degradation of cartilage, fragments of C-terminal crosslinked telopeptide type II collagen (CTX-II) are being released into circulation and subsequently secreted into urine. Therefore, (CTX-II) is considered as a potential biomarker for cartilage degradation and disease progression. In multiple studies, urinary CTX-II has bee reported to be useful in progression of osteoarthritis, early indiation of rheumatoid arthritis as well as other clinical / pre-clinical investigations.
Principle of Test Method:
The urinary CTX-II assay is a solid-phase ELISA that employs the competitive enzyme immunoassay principle. CTX-II is reported as a normalized ratio to urinary creatinine in order to account for variations in urine flow rate. Therefore CTX-II and urine creatinine are preferably tested from the same aliquot.