General Information, Immunochemistry

P1NP (Procollagen Type I Intact N-terminal Propeptide) Update

Effective June 17, 2019, Procollagen 1 intact N-terminal  (P1NP) testing will change from a sendout reference radioimmunoassay test to Mayo Medical Laboratories to an in-house chemiluminescence assay performed by Spectrum Health Regional Laboratory.

During bone formation, osteoblasts make collagen in the form of procollagen, with propeptide extensions removed during synthesis which can be measured in the serum, including the amino terminal, P1NP.  This test is reported to be the most specific and sensitive marker of bone formation, especially helpful in monitoring bone health and the efficacy of osteoporosis therapy, both with bone formation therapies and antiresorptive therapies.  Some experts recommend baseline testing before osteoporosis therapy begins with follow-up testing at 3-6 months to evaluate progress.

P1NP values should not be used as a screening test for osteoporosis in the general population.  There is a possible reported diurnal variation of P1NP levels, with the values being higher at night. When serial measurements of P1NP are performed, specimens should be collected at the same time of the day. P1NP is metabolized in the liver. In individuals with severe liver disease, clearance from the circulation might be affected resulting in elevated P1NP levels.

This test was developed and its performance characteristics determined by Spectrum Health Regional Laboratory. It has not yet been cleared or approved by the FDA.  This laboratory is regulated under CLIA as qualified to perform high-complexity testing.  This test is used for clinical purposes in conjunction with other medical diagnostic procedures.

The new reference range at Spectrum Health for P1NP is:

  • Adult patients age 18 and over:                  23-83 mcg/L

The new reference range is similar to the previous reference ranges from Mayo Medical Laboratories:

  • Adult male:                                                      22-87 mcg/L
  • Adult female premenopausal:                     19-83 mcg/L
  • Adult female postmenopausal :                  16-96 mcg/L


P1NP (Procollagen 1 Intact N-terminal Propeptide): Epic Code: LAB1230524,  Interface Code: 1230524, CPT Code: 82523


J Lee and S Vasikaran  “Current recommendations for laboratory testing and use of bone turnover markers in management of osteoporosis” Ann Lab Med 2012;32:105-112

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