Vitamin D deficiency: To test or not to test

Morgan Liotta

1/08/2023 2:43:26 PM

What should GPs say to patients who request vitamin D tests that are not clinically indicated?

Blood vial for vitamin D test
The RACGP does not recommend to routinely measure vitamin D in the general population.

During the winter months, particularly in the southern states of Australia, vitamin D levels naturally decrease as people spend less time outside.
But patients may still request a vitamin D test, so how can GPs best manage these requests when the test is not clinically indicated?
The RACGP’s First do no harm: A guide to choosing wisely recommends that GPs do not routinely measure vitamin D in the general population, with a specific topic resource providing guidance for GPs to have a conversation with their patients about vitamin D testing, as well as the corresponding patient-facing resource.
‘Whether vitamin D testing is or is not important depends on the clinical context,’ Dr Michael Tam, member of the RACGP Expert Committee – Quality Care (REC–QC) and Co-Chair of the First Do No Harm Expert Steering Group, told newsGP.
‘In general terms, it is only useful when the result of the test can inform a change in clinical care, where that change will meaningfully have a positive impact on the patient’s health.’ 
The First do no harm guide is designed to reduce overdiagnosis, interventions with insufficient evidence and overused tests, and facilitate shared decisions about health between GPs and their patients. Each topic has a GP and patient resource.
Professor Mark Morgan, who is Chair of the REC–QC and also Co-Chair of the Expert Steering Group, agrees that testing vitamin D is not routinely recommended unless there are risk factors for deficiency.
‘Vitamin D is a commonly requested test and it is sometimes added to a battery of tests with little expectation of benefit from doing the test,’ he said.
‘There are economic and environmental concerns from requesting low-value tests.’
The resource on testing for vitamin D deficiency recommends GPs do not routinely measure vitamin D in the general population, for reasons that include the following:

  • vitamin D deficiency does not have a universally defined lab value
  • over-screening of patients for vitamin D deficiency increases healthcare costs compared to supplementation
  • vitamin D levels will naturally be low during winter, and higher during summer, so it may be an unnecessary supplementation.
However, according to Dr Tam, vitamin D testing is important for people with risk factors, and there are ‘a range of reasons’ for when the tests may be appropriate. He says testing will only be funded by the MBS if the patient meets specific MBS criteria.
The RACGP recommends if a patient requests the test, GPs can explore their reasons for doing so and if they have any risk factors while explaining the MBS criteria.
The guidance also includes recommendations for GPs to:
  • explain the role of vitamin D in bone health, and provide standard lifestyle advice about maintaining bone health, including weightbearing exercise, maintaining a healthy weight range, ensuring adequate dietary intake of calcium and vitamin D, participating in outside activity with safe sun exposure, taking measures to prevent falls, quitting smoking and reducing alcohol consumption
  • treat physical symptoms – ask about patients’ expectations of the current treatment of their conditions, and re-emphasise MBS criteria for testing
  • consider osteoporosis risk factors and testing, if relevant – refer to the Guidelines for preventive activities in general practice (Red Book) which is currently being updated
  • continue to encourage normal general practice care.
Professor Morgan said GPs should apply ‘respectful, evidence-informed communication’ when patients request tests, while Dr Tam said it is also important to explore with the patient why they requested the vitamin D test.
‘For instance, what are their ideas, concerns and expectations? In a certain sense, few if anybody wants to have a vitamin D test in and of itself, but rather, they want something that they believe the vitamin D test will do for them,’ he said.
‘By understanding the reasons for the request, we can often work together with our patients to meet those health needs.  
‘We encourage our members to use the patient/consumer facing resource with their patients.’
When using the First do no harm resources, GPs can create a quick log to self-record CPD points.
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A.Prof Christopher David Hogan   2/08/2023 9:05:09 PM

If an abnormally low level of Vit D is detected an important condition to check for is Coeliac Disease