Study sheds light on “low-value” vitamin D tests.

Doctors are ordering unnecessary, costly and invasive blood tests for children to detect vitamin D deficiency, when simple preventative steps should instead be taken to ensure children are getting supplements of the essential nutrient, according to research conducted by Macquarie University.

Vitamin D deficiency, especially during the first 12 months of life, puts babies at risk of developing nutritional rickets, a potentially disabling and, on rare occasions, fatal disease. To avoid this, current global recommendations state that all children should receive vitamin D supplements for the first 12 months of life, but routine testing for vitamin D levels is not recommended in children without symptoms. But according to the researchers, fewer children would benefit from taking the supplements for longer.

A study of 61,809 blood tests asking for vitamin D levels in 46,960 children and adolescents presenting to general practitioners in Victoria found that the likelihood of a child having a vitamin D blood test in 2018 was 30 times greater than in 2003, a huge increase. But the possibility of detecting a vitamin D deficiency remained the same.

Even when vitamin D deficiency was detected, only 4 percent of the children were followed up within three months to see if their vitamin D levels had improved.

“All of this testing seems counterintuitive and is symptomatic of low-value care,” says Professor Yvonne Zurynski, professor of health system sustainability at the Australian Institute of Health Innovation and one of the study’s lead authors.

Prevention versus testing

The study was published in the journal Archives of disease in childhood. It follows an earlier recommendation from an international expert panel that testing for vitamin D deficiency without clinical signs was unnecessary. This advice does not appear to have taken root in general practice in Australia, says Professor Zurynski.

“General practitioners need more education on the latest global evidence-based guidelines so that prevention rather than testing is their first choice and patients receive care based on best practice,” says Professor Craig Munns , co-author of the study.

Professor Munns is director of the Child Health Research Center at the University of Queensland, pediatrician at Queensland Children’s Hospital and honorary professor at Macquarie University.

Children with vitamin D deficiency have serious clinical complications, says Professor Munns.

“It’s a spectrum. You can go from being completely asymptomatic, to having vague aches and pains, to having nutritional rickets, to having hypocalcemia (very low calcium), and then having a seizure. Thankfully, the severe end of the spectrum is very rare.” .”

Clinically, children with rickets bones may be reluctant to walk because their legs hurt or they tire easily. They may have skeletal deformities such as thickening of the ankles, wrists, and knees, bowed legs, soft skull bones, and, rarely, flexion of the spine.

The main source of vitamin D in Australia comes from sun exposure. In summer, even a relatively small amount is adequate. When skin is exposed to ultraviolet light from the sun, it creates vitamin D. People with darker skin are at a higher risk of developing vitamin D deficiency, says Professor Zurynski.

“Breast milk alone does not contain adequate amounts of vitamin D,” says Professor Zurynski.

“If a child is covered in clothes or on too much sunscreen the entire time they go out, they may be getting very little from sun exposure.”

Professor Munns was the lead author of a study by 33 global experts in 2016 that created the Global Consensus Recommendations on the Prevention and Management of Nutritional Rickets.

These international guidelines recommend that physicians “universally supplement all infants with vitamin D from birth to 12 months, regardless of their feeding pattern.”

Many countries have adopted these guidelines, including the United States, Canada, the United Kingdom and Europe, and food products in these countries are also fortified with vitamin D.

Australia has yet to adopt these recommendations nationally, although some local government health authorities have adopted them and none of our foods are fortified with vitamin D.

Professors Munns and Zurynski are part of a group of Australian experts pushing for the recommendations to be adopted here.

There are still cases of vitamin D deficiency in Australia, says Professor Munns, leading to around 4.9 cases of rickets per 100,000 children, compared with 2.9 cases per 100,000 children in Canada and 7.5 cases per 100,000 children in the UK.

‘If we gave all babies vitamin D supplements for the first 12 months of life, then we would eliminate it, just like we did by giving pregnant women folate to prevent spina bifida. It’s within our reach,’ Professor Munns says .