Skip to content
Blood Test Tracker

P1NP (Procollagen Type 1 N-Terminal Propeptide)

A blood marker of how fast new bone is being built. It is mostly used to follow bone treatment, not to screen healthy people.

AI-verified against cited sources. Awaiting expert reviewAlso called P1NP, PINP, tP1NPLOINC 47255-5

Check your result

Sex (optional)

The usual range for P1NP depends on sex. Choose female or male above to see where you stand.

Nothing you type here leaves your browser.

What it is

Bone-building cells make collagen, the main protein in bone. As new collagen forms, a small piece called P1NP is clipped off and passes into the blood. So the level reflects how quickly new bone is being made. Some labs measure total P1NP and others measure intact P1NP. The two are close but not identical.

Why it matters

P1NP and CTX are the two bone markers that expert groups recommend for tracking bone turnover. P1NP is mostly used to see whether osteoporosis treatment is working, by comparing a result from before treatment with one taken a few months later. It cannot diagnose osteoporosis and does not replace a bone density scan.

If it’s low

A lower P1NP means less new bone is being built. P1NP also falls with medicines that slow bone loss, because bone building slows a few weeks after bone breakdown does.

Common causes

  • Normal variation in a healthy adult, since lab ranges don't fit everyone
  • Medicines that slow bone breakdown, which lower P1NP a few weeks after they lower CTX

What can help

  • Ask your clinician whether this fits the bone treatment you are on
  • Stay active with weight-bearing exercise and eat enough calcium and vitamin D

If it’s high

A higher P1NP means more new bone is being built than usual. That is expected in children and teenagers, after menopause, while a broken bone heals, and with bone-building medicines. It can also be higher with conditions that speed up bone turnover. P1NP does not show how strong your bones are.

Common causes

  • Growth: children and teenagers have much higher levels than adults
  • Menopause, when bone turnover speeds up (P1NP can rise by about half)
  • Healing after a fracture (bone markers can stay raised for months)
  • Medicines that build bone, which raise P1NP on purpose
  • Paget's disease of bone, an overactive parathyroid gland, or cancer that has spread to bone
  • Advanced kidney disease, which can make total P1NP read higher

What can help

  • Ask your clinician how to read this result alongside a bone density scan, calcium, vitamin D, PTH and kidney function
  • If you have had a recent fracture, ask whether the result may just reflect healing
  • Stay active with weight-bearing exercise and eat enough calcium and vitamin D

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on sex. Choose women or men to see the one that applies.

What can affect your result

  • Age: much higher in children and teenagers, then steady through adult life
  • Menopause: P1NP rises by about half afterward
  • Recent fracture: raised for months
  • Kidney function: in advanced kidney disease, total P1NP builds up because the kidneys clear it more slowly
  • Time of day: only a small daily swing (about 3% to 5%), much less than CTX
  • The assay (total or intact) and the lab
  • Bone-building and bone-protecting medicines
  • A recent fracture raises bone markers for months (up to about 6 months after minor fractures and up to a year after a hip fracture).
  • Advanced kidney disease can make total P1NP read higher, because the pieces clear more slowly.
  • Total P1NP (Roche) and intact P1NP (IDS, Orion) assays give close but not identical results, so compare results from the same lab and method.
  • Hemolyzed or very fatty (lipemic) samples are rejected by labs such as Quest and ARUP. ARUP accepts serum only, not plasma.

Any time of day works for most assays, but use the same time each visit. ARUP asks for a consistent draw time because values are higher at night. Changes within about 3 months of starting a bone-building or bone-protecting treatment.

When to talk to a clinician

A P1NP result is rarely urgent on its own. Talk with your clinician if it is well above your lab's range and you have a recent fracture or new bone pain, or if you take bone treatment and have not gone over the result.

Questions you could ask

  • Should I have a baseline P1NP before starting any bone treatment?
  • Does it matter whether my lab measures total or intact P1NP?
  • Could menopause, a recent fracture or my kidney function explain this result?
  • How does this fit with my bone density scan and my other bone tests?
  • Is this what you expected from my bone treatment?
  • When should we recheck it, and should it be at the same lab and time of day?

Questions people ask

Do I need to fast for a P1NP test?

Usually not. P1NP changes little with meals or the time of day, unlike CTX. Even so, use the same lab, and if you can, the same time of day, so results can be compared. Some labs ask for the same time of day each visit.

What is the difference between total and intact P1NP?

Intact assays pick up only the whole three-part molecule. Total assays pick up the whole molecule plus single pieces. Results are close in people with healthy kidneys but not identical, and total P1NP can read higher when the kidneys are not working well. Stick with one lab and method.

Does a normal P1NP mean my bones are healthy?

Not necessarily. P1NP shows how fast bone is being built, not how strong it is. Bone density scans, your fracture history and your other risk factors tell your clinician much more about bone strength.

Show the science and sources

Units

  • 1 ng/mL = 1 ng/mL
  • 1 ng/mL = 1 µg/L

Is a change real?

P1NP naturally varies about 8.8% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 26% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: The European Biological Variation Study (EuBIVAS): a summary report.

For clinicians and researchers

P1NP is the N-terminal extension of type I procollagen. It is cleaved off outside the cell as collagen is laid down, so it tracks osteoblast collagen synthesis. Blood holds the intact trimer (iPINP) and monomer fragments; assays recognize either the trimer alone (intact assays such as IDS-iSYS and Orion UniQ) or both (total assays such as Roche). Roche and IDS values are similar, and Orion values run lower (Schini 2023). IOF and IFCC (2011) named serum P1NP the reference marker of bone formation, and a 2025 ESCEO/IOF/IFCC update re-affirmed it. P1NP has minimal daily variation (about 3% to 5%) and is little affected by food (a fall of about 4% to 10% after a meal), so sampling at any time and fasting state is acceptable. Total P1NP can read falsely high in advanced CKD (stages 4-5 and dialysis) because of renal retention of the monomer, while intact P1NP is considered usable in CKD; KDIGO 2017 suggests not routinely measuring collagen synthesis markers in CKD G3a-G5D. Healthy-adult intervals are fairly consistent across assays: in 637 premenopausal women aged 30 to 39 on the Roche assay the interval was 16.3-78.2 ug/L. Bone-building medicines raise P1NP and bone-protecting medicines lower it, with changes visible within about 3 months (Wheater 2013). Treatment targets for P1NP are not firmly established, so none is given here. No published critical value was found.

LOINC 47255-5 (primary), 77370-5. Specimen: serum-or-plasma.

Sources

  1. Procollagen Type I Intact N-Terminal Propeptide (test 0070236), ARUP Laboratories
  2. Procollagen Type I Intact N Terminal Propeptide (test code 16609), Quest Diagnostics
  3. Bone Turnover Markers: Basic Biology to Clinical Applications, Endocrine Reviews (2023)
  4. Update on the role of bone turnover markers in the diagnosis and management of osteoporosis: a consensus paper from ESCEO, IOF and IFCC, Osteoporosis International (2025)
  5. Use of CTX-I and PINP as bone turnover markers: National Bone Health Alliance recommendations to standardize sample handling and patient preparation to reduce pre-analytical variability, Osteoporosis International (2017)
  6. Markers of bone turnover for the prediction of fracture risk and monitoring of osteoporosis treatment: a need for international reference standards, Osteoporosis International (2011)
  7. The clinical utility of bone marker measurements in osteoporosis, Journal of Translational Medicine (2013)
  8. KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), Kidney International Supplements (2017)
  9. Osteoporosis, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIH)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

Related markers