External quality assessment of bone metabolism marker assays. initial experiences in a UK NEQAS programme

This paper reports on a pilot external quality assessment scheme for bone markers including serum bone alkaline phosphatase and procollagen 1-carboxy terminal propeptide together with urine deoxypyridinoline, N- and C-telopeptides. The data shows poor numerical agreement between commercial assays, between-laboratory imprecision that could be improved, and the need for international standardisation of assays.