Procollagen type I N-terminal propeptide (PINP)
Collagen type I (PINP)is present in soft connective tissues and bone, where it constitutes more than 90% of the organic matrix. During bone formation, PINP is synthesised from pro-collagen type I, which is secreted from fibroblasts and osteoblasts.
Increasing rate of elderly population in the world, makes bone metabolism related diseases one of the top ten common diseases. Therefore, bone metabolism is a hotspot in medical researches. The measurement of PINP is a sensitive means of assessing bone turnover. Currently, a large number of studies have shown that PINP, is closely related to a variety of bone metabolic diseases, tumor bone metastasis and multiple myeloma. Also, the level of PINP has been found to correlate with and precede changes in Bone Mineral Density (BMD), and to predict the rate of bone loss. And its detection is not affected by food, circadian rhythm, hormones and other interference factors.
Bone turnover consists of two tightly regulated events; bone resorption and bone formation mediated by osteoclasts and osteoblasts respectively. The two events are coupled so that the same amount of bone is formed than being resorbed. This maintains the density and amount of bone.