Has your doctor urged you to have your vitamin D level checked recently? It happens a lot these days: Many doctors have made this test a standard part of a routine checkup.

The only problem: Most health experts have been saying for almost five years now that widespread screening for vitamin D deficiency is unnecessary.

Now, researchers have found they could slash the number of vitamin D tests by forcing doctors to answer a single, simple question: Why are you ordering it?

The Problem With Unnecessary Testing

Low levels of vitamin D are known to interfere with bone health, but widespread screening of healthy people for low vitamin D levels is not supported by the medical evidence.

National medical specialists in blood tests said so in 2013 as part of the Choosing Wisely campaign, and a group of national experts in disease prevention agreed with this in 2014. Both say that it's unclear exactly what constitutes low levels of D and, more important, whether taking vitamin D supplements to raise those levels actually helps.

So getting tested when it's not needed is not only a waste of time, but can be a waste of money, too, in terms of office co-pays and dietary supplements.  

Health officials in Alberta, Canada—where 1 in 14 people now get screened for low vitamin D levels annually—decided to reduce that testing by requiring doctors to check off the medical reason they were ordering the test. 

The checklist included just those conditions for which testing is known to be justified: metabolic bone disease, abnormal blood calcium levels, nutrient absorption problems such as celiac disease, chronic kidney disease, and liver disease.

Testing dropped 92 percent immediately, and stayed down. (Taxpayers are saving $4 million a year.)

"There was minimal pushback from patients," says Robert Ferrari M.D., of the University of Alberta, whose report of the project was published in the journal JAMA Internal Medicine. "The problem lay with the physicians in the first place."

CR's chief medical adviser, Marvin M. Lipman M.D., says the result is encouraging. "When indications for tests are specific, and not left to the imagination, test ordering tends to decrease."

What to Do Instead

If your doctor offers to send you for a blood test for vitamin D, you can ask the same question: Why? Ask about your risks of bone disease from low vitamin D levels. If your risk is high, you should get the test. If your risk is low, ask if you can avoid the test. 

Then take steps to make sure you're getting enough vitamin D. Sources include sunlight on your skin, certain foods that are rich in vitamin D (fatty fish, eggs, and fortified milk and orange juice), and fortified foods.