The Procollagen Type 1 Intact N-Terminal Propeptide (P1NP) test is the most sensitive and precise marker of bone formation. It helps monitor bone health and the effectiveness of osteoporosis therapy.  Osteoporosis is a silent condition that results in the weakening of bones. It makes the bones more vulnerable to sudden and unexpected fractures. This ailment progresses without any pain and cannot be detected until the bones fracture. The P1NP test helps track antiresorptive and anabolic therapy in patients with osteoporosis. P1NP Test - Overview P1NP is a peptide derived from collagen type 1—the most common collagen found in mineralised bone.  In the human bone, osteoblasts are responsible for synthesising collagen and leading to the formation of procollagen. It also consists of a short signal sequence along with terminal extension peptides. The removal of these extensions is done before the collagen molecules are formed. Owing to this formation, P1NP is regarded as one of the most sensitive markers used for bone formation. It also finds wide use in monitoring response to medicines used for the treatment of osteoporosis. The P1NP test is recommended to be performed before starting osteoporosis therapy. The procedure is required again 3-6 months after the therapy. The change in the P1NP levels will depend on the type of treatment. Combining it with other procedures like hormone replacement therapy leads to a decrease in P1NP levels, thereby decreasing its effects. P1NP should not be considered a screening test for osteoporosis. It is important to collect the P1NP values at the same time since they are believed to show diurnal variation. Why Should You Get Tested? P1NP is a reliable test that effectively monitors your bone health and delivers accurate results. The sensitivity of this test assists with tracking bone formation and assessing response to antiresorptive therapies used for osteoporosis. It might be challenging to detect osteoporosis in the initial stages. However, some of its common symptoms include: Back pain Loss of height over time Stooped posture Brittle bones The P1NP blood test is a flexible procedure that can be performed on everyone, irrespective of age or gender. It is always recommended to consult your doctor to ensure that you can take the test safely.    Medically reviewed by Dr. Arun Kannan, Orthopedician from Apollo Hospitals Greams Road, Chennai.