Table 2.

Longer term actions required to improve the international comparability of PTH results

Priority	Action
1	Confirm support for and then commence an international PTH assay re-standardization project based on IS 95/646. A detailed protocol should be produced as part of the process of gaining support. Funding and the resulting educational support will be incorporated in the project.
2	Establish a panel of samples of defined clinical provenance covering normal hypercalcaemic and CKD patients that could be used by all manufacturers to determine reference intervals and clinical decision points. Assign values to these samples—initially based on consensus means but subsequently based on a reference measurement procedure (see below).
3	Identify an expert group that could establish a candidate reference measurement procedure for PTH (probably based on mass spectrometry). Seek funding and international support to enable establishment and validation of the candidate reference measurement procedure.
4	Establish a group to examine existing and new evidence about the clinical requirements of a PTH assay and the performance goals to meet those requirements. Issues considered should include bias, imprecision, specificity (bio-intact versus intact) and biological variation.