Inappropriate trace element testing in the Auckland region

To understand recent changes in trace element test usage in the Auckland region of New Zealand.

Laboratory records of trace element tests between 2004 and 2008 were analysed. A questionnaire was sent to a frequent requestor group to elicit reasons for requesting trace element tests.

The annual number of trace element test requests increased by 3.5-fold over the study period. The increase was largely due to a 2.8-fold increase in serum copper, a 3.8-fold increase in serum zinc, and a 3.4-fold increase in serum selenium tests. Most of the increase was accounted for by a small number of requestors, mainly general practitioners. An outlier group of 24 requestors was identified who were responsible for ordering 55% of serum copper, 61% of serum zinc, 63% of serum selenium and 66% of blood mercury tests in the last year of the study. Responses to the questionnaire suggest that among the outlier group the reasons for requesting serum zinc, copper and selenium tests are not evidence-based.

The majority of trace element tests performed in the Auckland region appear to be non-evidence-based, and represent a significant wastage of public laboratory resources. This suggests that laboratories could achieve significant savings in expenditure by clearly defining appropriate indications for performing trace element tests.