Harmonising Adult Reference Intervals in Australia and New Zealand - the Continuing Story.

Reference intervals (RIs) are used to help clinicians determine if a patient can be classified as being in a diseased or healthy state and there are often sound scientific and clinical reasons for differences in RIs. One of the current strategic priorities for the Australasian Association of Clinical Biochemists is to encourage and assist laboratories to achieve harmonisation of RIs for common clinical chemistry analytes where sound calibration and traceability are in place. This need is based on good laboratory practice, providing the clinician with results that allow appropriate and reliable clinical interpretation and progression further toward the national e-health framework and a single electronic health record. After reviewing and considering studies related to bias as well as both a priori and a posteriori RI studies nationally and internationally and the consideration of flagging rates and clinical relevance, an initial group of 12 harmonised RIs were endorsed by the Royal College of Pathologists of Australasia in 2014. In 2015, after further stakeholder consultation, a second group of six harmonised RIs for common chemistry analytes has been proposed for adults which includes ALT and AST where methods do not use pyridoxal-5'-phosphate as an activator and lipase excluding the Ortho Clinical Diagnostics and Siemens Dimension assays.