Greater consideration needed by doctors before ordering vitamin D tests

12 April 2011 

Testing for vitamin D has increased more than tenfold in the last five years, with test orders rising at a faster rate than any other medical test. This surge is likely due to increased GP interest in vitamin D deficiency, media reports of its high prevalence in Australia and its suggested role in a range of health conditions.

NPS’s latest education program for health professionals provides guidance around common questions being asked about vitamin D deficiency including who is at risk, when is testing of value and appropriate supplementation for those who are deficient.

“There is a lot of conflicting information regarding vitamin D. In the absence of clear Australian guidelines, this NPS education program provides direction on how to identify and manage people at risk of vitamin D deficiency and those who are not, and factors that may influence the vitamin D results you receive. It also addresses supplementation as a treatment option in addition to safe sun exposure,” NPS clinical adviser, Danielle Stowasser said.

There are a number of different tests used in Australia to determine vitamin D levels and there has been a considerable degree of variability between the tests and between laboratories. In some studies, a substantial minority of blood samples have been classified as having adequate vitamin D levels by one assay or laboratory but deficient by another assay or laboratory.

“Awareness of these limitations of vitamin D testing appears to be low among health professionals. While new international standards and quality assessment programs should amend this, doctors should be aware of these current limitations and variables,” Dr Stowasser said.

The type of association between vitamin D deficiency and non-bone diseases such as type 2 diabetes, hypertension and others is also yet to be proven.

“This NPS program encourages assessment of risk through a targeted approach to testing rather than screening patients for vitamin D deficiency. The benefit of routine testing in low-risk populations is unclear, and studies show moderate to severe vitamin D deficiency is uncommon in the general Australian population.”

However, there are a small number of groups who are at risk of deficiency and for whom vitamin D testing and supplementation is advisable. These include people:

  • who are housebound, particularly those over 65 years or living in aged care facilities
  • with naturally dark skin
  • who cover themselves for religious or cultural reasons.

The following resources and activities about vitamin D are available for health professionals:

For more information visit


Independent, evidence-based and not-for-profit, NPS enables better decisions about medicines and medical tests.We are funded by the Australian Government Department of Health and Ageing.