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Vitamin D testing rates fall in New Zealand


The rates of unnecessary vitamin D testing in New Zealand have dropped by a staggering 70 per cent since 2010, thanks to the implementation of new testing guidelines, a leading pathologists’ group says.

The Royal College of Pathologists of Australasia’s Dr Michael Crooke says the rapid decline in unnecessary vitamin D testing in New Zealand is a direct result of the new recommended clinical guidelines.

“The recommended clinical guidelines on vitamin D testing have led to an extremely positive effect on the way in which these tests are requested in New Zealand,” Dr Crooke said.

“Seeing this dramatic reduction first-hand has confirmed our views on the excessive nature of a large proportion of these requests.

“I would suggest that, over time, it is highly likely that vitamin D tests will continue to decrease further.”

A study released last year in the British Medical Journal found that the rate of vitamin D testing in Australia increased 94-fold from 2000 to 2010. Eighty per cent of the tests were ordered by GPs and 20 per cent by specialists.

The study’s authors concluded that the rate of testing for vitamin D was increasing “exponentially at an unsustainable rate” and that the consequences of such over-testing were widespread in terms of costs and effectiveness.

The RCPA released a position statement on the measuring and monitoring of vitamin D in May 2013 in which they recommended against routine screening for deficiency.

The rate of testing increased following concerns that many cases of vitamin D deficiency were being missed.

Australian Medicine previously reported that research conducted by the Baker IDI Heart and Diabetes Institute estimated that 31 per cent of Australian adults had a vitamin D deficiency, which was assessed as severe in 4 per cent of cases, while a separate NSW-based study reported that up to 58 per cent of adults might have a deficiency of the vitamin.

The consequences of deficiency can be severe, according to the Department of Health and Ageing. It says prolonged deficiency could cause rickets in children and osteoporosis and softening of the bones in adults. It can also be associated with chronic kidney disease, Crohn’s disease, and cystic fibrosis.

Speaking on the latest drop in testing rates in New Zealand, RCPA spokesperson, Dr Paul Glendenning, says routine testing for vitamin D is unnecessary for people with an active lifestyle.

“The previously seen increase in vitamin D testing is unsustainable,” Dr Glendenning said. “The RCPA recommends that vitamin D testing is not performed as routine screening.

“As the main source of vitamin D is UVB sunlight exposure, vitamin D levels are correlated with time spent outdoors, exercise and other aspects of a healthy lifestyle, including body weight. For healthy adults, infants and pregnant women who don’t have any other risk factors for vitamin D deficiency, we do not currently recommend routine screening.”

Dr Glendenning added, however, that people at particular risk of vitamin D deficiency should be tested on a case-by-case basis

“It’s justifiable to test those individuals who have a higher risk for vitamin D deficiency. Routine screening is not currently justified, so a case-finding strategy is appropriate.”

Clinical guidelines in New Zealand differ slightly to Australia in this area, with some patients in the high risk category for deficiency being routinely supplemented without undergoing vitamin D testing.

Debra Vermeer