Assessment of bone turnover in osteoporosis: harmonization of the total testing process

Abstract An imbalance between bone formation and bone resorption is a factor in the development of osteoporosis. Bone turnover markers (BTM) are useful in assessing bone remodeling at the cellular level. Measurement of BTM is useful for assessing bone turnover and therefore fracture risk as well as for monitoring response to treatment response. This paper describes the steps that have been taken so far and the ongoing work to harmonize the total testing process for the assessment of bone turnover in osteoporosis internationally and collaboratively between the clinical and laboratory professions. The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) in collaboration with the International Osteoporosis Foundation (IOF) as well as the National Bone Health Association (NBHA) in the US have designated procollagen type I N propeptide (s-PINP), and cross-linked β-isomerized type I collagen C-telopeptide (s-βCTX), in blood as reference standard BTM. Collaborative efforts are ongoing in order to standardize preanalytical steps as well as the analysis of s-PINP and s-CTX by standardizing or harmonizing their measurement as appropriate and reporting of values. Reporting units have been standardized. Reference interval studies and examination of appropriate decision thresholds, reference change values and treatment targets are ongoing with the aim of harmonizing the total testing process for the assessment of bone turnover in osteoporosis.