Serum P1NP levels are tested mainly to monitor patients with osteoporosis who are being treated specifically with teriparatide medication. Throughout our lifetime, our bones undergo constant transformation (known as turnover) as bone tissue is continuously being destroyed and renewed in a process we call bone remodelling (or bone metabolism). This process takes place in two phases: the first phase (resorption) is the “destruction” of a small part of mature bone tissue, and it is followed by the second phase (formation), which involves its replacement by new bone tissue. In patients with osteoporosis, the bones are weakened because the resorption process takes place at a faster rate than the formation process.
Osteoporosis can be corrected in two ways: by blocking bone resorption with medications such as bisphosphonates, or in the case of more severe osteoporosis (high risk of fractures), by directly stimulating new bone formation with teriparatide (Forteo©). When bone tissue is renewed, small fragments of the new collagen are found in the bloodstream, including P1NP. The higher the P1NP level in the blood, the more bone formation is taking place. P1NP levels rise within a few weeks when osteoporosis is being treated successfully with teriparatide.