We commend the authors of this report that highlight the increasing trend for overdiagnosis of medical conditions. The authors cite several examples and in particular certain endocrine disorders (1).

We would like to report that similar concerns for overdiagnosis and overtreatment need to be raised for vitamin D deficiency (2). At present there is no agreement as to the appropriate timing and frequency of testing for the diagnosis of 25OHD deficiency. We have recently reported that the cost of testing in Australia has increased from $1M in the year 2000 to $95.6M in the year 2010, or on average 59% each year. (3) A small report from the United States indicated that testing for 25OHD had increased by 80-90% per year. (5) Similarly, in Ontario, Canada testing increased 25-fold from 2004 to 2010. Projected figures from that report estimated that $150M will be spent on 25OHD testing in 2012, up from $38M in 2009. (6) Similarly, the United Kingdom has seen a six-fold increase in 25OHD tests between 2007 and 2010. (7)

Our data demonstrates that there has been an unsustainable growth in 25OHD testing across Australia over the last 11 years (see Figure). The consequences of our findings are widespread in terms of quality of care, unnecessary cost and potential overdiagnosis. Further studies are required to determine whether this increased testing translates into improved 25OHD status of the population and subsequent health outcomes. A worrying trend, however, is that despite the magnitude of the rise in 25OHD testing this did not translate into increased testing for osteoporosis, as evidenced by the flat trend in bone density measurements (Figure).

Guidelines are urgently needed to limit over testing and as a consequence over treatment for vitamin D testing.

1. Moynihan R, Doust J, Henry D. Preventing overdiagnosis: how to stop harming the healthy. Bmj. 2012;344:e3502.
3. Boyages S, Bilinski K. Seasonal reduction in vitamin D level persists into spring in NSW Australia: implications for monitoring and replacement therapy. Clinical endocrinology. 2012 Apr 3.
4. Bilinski KB, Boyages S. The rising cost of vitamin D testing in Australia: Time to establish guidelines for testing. Medical Journal of Australia. 2012;Accepted.
5. Singh RJ. Are clinical laboratories prepared for accurate testing of 25-hydroxy vitamin D? Clin Chem. [Letter]. 2008 Jan;54(1):221-3.
6. Mittelstadet M. Ontario considers curbing vitamin D testing. The Globe and Mail [serial on the Internet]. 2010.
7. Sattar N, Welsh P, Panarelli M, Forouhi NG. Increasing requests for vitamin D measurement: costly, confusing, and without credibility. Lancet. 2012 Jan 14;379(9811):95-6.

Competing interests: None declared