COL1A2 and osteoporosis: Total Ocn has not been used since 2011 when the International Osteoporosis Foundation and the International Federation of Clinical Chemistry and Laboratory Medicine recommended that the procollagen type I N-terminal propeptide (P1NP) be used as a marker of formation and the carboxyl‐terminal cross linking telopeptide of type I collagen I (CTX-1) as a marker of resorption in clinical studies on osteoporosis (34, 44).