Total type I collagen amino-terminal elongation peptide TPINP is one of the monitoring indicators of bone metabolism, which can be used for the diagnosis of tumor bone metastasis, judgment of bone metabolism of type 2 diabetes mellitus, osteoporosis and other items. 1. Physiological significance: Serum TPINP can reflect the activity of osteoblasts and the rate of bone formation. This index has high specificity and good stability for bone density changes, and is a sensitive index for artificial assessment of bone quality. 2.Clinical application (1) Diagnosis of tumor bone metastasis: serum TPINP increases significantly with the number of bone metastases, which is closely related to the development of the disease. (2) Determination of bone metabolism in type 2 diabetes mellitus: serum TPINP in type 2 diabetes mellitus is significantly lower than that in healthy people, suggesting that high blood sugar may inhibit osteoblast activity and reduce bone formation. (3) Detection of osteoporosis: TPINP can effectively assess the early treatment, prevention and complications of osteoporosis; TPINP levels in peripheral blood of patients with fractures caused by osteoporosis were significantly higher. Abnormalities of total type I collagen amino-terminal extender peptide are recommended to go to the hospital in time.