A REVIEW ON BIOMARKERS OF BONE METABOLISM IN CAMELS (Camelus dromedarius)

Bone metabolism biomarkers of bone formation and bone resorption are released during the bone remodeling processes. In humans as well as in veterinary medicine, these bone biomarkers have attracted much attention in the last decade. However, there are few reports found in the application of bone metabolism biomarkers in camel medicine. In camels, the most commonly used bone formation biomarkers include osteocalcin (OC) and bone-specific alkaline phosphatase (b-ALP). Concerning the bone resorption biomarkers, the most commonly used one is pyridinoline cross-links (PYD). OC is synthesised mostly from by mature osteoblasts. It is believed that OC is associated with mineralisation of newly formed osteoid. Therefore it is considered as a putative biomarker of bone formation and mineralisation. b-ALP is an isoform of alkaline phosphatase and plays an important role in bone formation. With normal liver function in adults, about 50% of total b-ALP is produced from bone in serum. The PYD cross-links, indicators of type I collagen resorption, are found in the mature collagen of bone. It is not only found in mature type I collagen, which is the major type of collagen in bone tissues, but also in collagen types II and III (Eyre et al, 1984). Increased concentrations of PYD in the blood or urine are most commonly considered as indicators of bone resorption. This review article was written to emphasise the importance of commonly used bone formation (OC and b-ALP) and bone resorption (PYD) biomarkers in camels. It is believed that research on bone formation and bone resorption biomarkers in camels will be increasingly used in the future in the diagnosis and prognosis of bone diseases.