![CDATA[ [if IE 9] ]]>
There is diurnal variation of PINP levels, with the values being higher at night. When serial measurements of PINP are performed, specimens should be collected at the same time of the day.
PINP is metabolized in the liver. In individuals with severe liver disease, clearance from the circulation might be affected resulting in elevated PINP levels.
Some patients who have been exposed to mouse antigens, whether in the environment or as part of treatment or imaging procedures, may have circulating antimouse antibodies. These antibodies may interfere with the assay reagents to produce unreliable PINP assay results.
Procollagen type I propeptides are derived from collagen type I, which is the most common collagen type found in mineralized bone. In bone, collagen is synthesized by osteoblasts in the form of procollagen. This precursor contains a short signal sequence and terminal extension peptides: amino-terminal propeptide (PINP) and carboxy-terminal propeptide. These propeptide extensions are removed by specific proteinases before the collagen molecules form. Both propeptides can be found in the circulation and their concentration reflects the synthesis rate of collagen type I. Although collagen type I propeptides may also arise from other tissues (such as the skin, vessels, fibrocartilage, and tendons), most nonskeletal tissues exhibit a slower turnover than bone, and contribute very little to the circulating pool of PINP. PINP is considered the most sensitive marker of bone formation and it is particularly useful for monitoring bone formation therapies and antiresorptive therapies; it is recommended that the test be performed at baseline before starting osteoporosis therapy and performed again 3 to 6 months later.
Reference values have not been established for patients who are <18 years of age.
Adult male: 22-87 mcg/L
Adult female premenopausal: 19-83 mcg/L
Adult female postmenopausal: 16-96 mcg/L