Количественное определение N-пептида III типа коллагена (PIIIP N-P)

The N-terminal propeptide of type I procollagen (P1NP, also called PINP or procollagen type I N-terminal propeptide) test assesses bone formation activity and overall bone turnover. It supports baseline characterization before anti-osteoporotic therapy, tracks response to treatment, and is useful when monitoring patients receiving teriparatide (parathyroid hormone analog). The assay also assists in longitudinal follow-up of individuals with osteoporosis, Paget disease, or osseous metastases and can help gauge activity of metastatic bone involvement and associated mortality risk.

Bone undergoes continuous remodeling, with osteoclast-mediated resorption balanced by osteoblast-driven formation; these dynamics are closely linked to calcium homeostasis and endocrine regulation by parathyroid hormone, pituitary, thyroid, adrenal, and gonadal hormones. Postmenopausal estrogen deficiency accelerates bone loss and fracture risk in women. Disordered remodeling is also characteristic of Paget disease of bone and skeletal involvement by metastatic malignancy, where biochemical markers help characterize disease activity and trajectory. Type I collagen constitutes roughly 90% of the bone organic matrix and is synthesized by osteoblasts as procollagen containing N- and C-terminal propeptides. During extracellular processing, specific proteases cleave these termini, releasing the fragments into interstitial fluid and blood as mature collagen incorporates into bone. Circulating P1NP is more stable and diagnostically informative than the C-terminal propeptide (P1CP), which degrades in blood within 6–8 minutes; serum P1NP concentrations reflect the rate of newly synthesized type I collagen incorporated into bone. Conditions with increased bone formation raise P1NP levels. Interpreting P1NP in conjunction with resorption markers (eg, B-CrossLaps, Pyrilinks-D), formation markers (eg, osteocalcin, alkaline phosphatase), and bone densitometry enhances assessment of bone status in postmenopausal osteoporosis, Paget disease, and metastatic bone disease.