Vitamin D tests: When you need them—and when you don’t

Vitamin D tests

Many people don’t have enough vitamin D in their bodies. Low vitamin D increases the risk of broken bones. It may also contribute to other health problems. That’s why doctors often order a blood test to measure vitamin D.

But many people do not need the test. Here’s why:

A test usually does not improve treatment.

Many people have low levels of vitamin D, but few have seriously low levels. Most of us don’t need a vitamin D test. We just need to make simple changes so we get enough D. We need to get a little more sun and follow the other advice on the next page.

Even if you are at risk for other diseases, like diabetes and heart disease, a vitamin D test isn’t usually helpful. The test results are unlikely to change the advice from your doctor. It is much more important for you to make lifestyle changes first—to stop smoking, aim for a healthy weight and be physically active. And, like most other Canadians, you should try to get enough vitamin D from sun and foods. And talk to your doctor about supplements.

Extra tests lead to extra treatments.

Getting tests that you don’t need often leads to treatments you don’t need, or treatments that can even be harmful. For example, if you take too much vitamin D, it can damage your kidneys and other organs.

When should you have a vitamin D test?

Talk to your doctor about your risks. Here are some conditions where you might need a Vitamin D test:

  • If you have osteoporosis. This disease makes your bones weak, so that they are more likely to break.
  • If you have a disease that damages your body’s ability to use vitamin D. These are usually serious and ongoing diseases of the digestive system, such as inflammatory bowel disease, celiac disease, kidney disease, liver disease and pancreatitis.

If your doctor suggests getting a vitamin D test, ask about your risks. If your risk is high, you should get the test. If your risk is low, ask if you can avoid the test. Ask if you can boost your vitamin D with sunlight and food, and possibly supplements.

If your doctor needs to keep track of your Vitamin D, make sure the same test is used each time. Ask your doctor which tests are best.


How can you get enough vitamin D?

The recommended dietary allowance (RDA) per day is 400 IU (10 mcg) for children <1 years of age, 600 IU (15 mcg) for persons aged 1-70 and those who are pregnant and lactating, and 800 IU (20 mcg) for persons older than 70 years old (http://www.hc-sc.gc.ca/fn-an/nutrition/vitamin/vita-d-eng.php).

Get some sun. The sun’s ultraviolet rays create vitamin D in your skin cells. You don’t need a lot of sun. Depending on the amount of skin exposed and sunscreen used, a 10-minute walk in the midday sun can create as much as 15 times the amount of vitamin D that you need every day. Your body stores some of the extra vitamin D to help you in the darker winter months.

Eat foods that are rich in vitamin D.

  • Meat, poultry and fatty fish are rich in vitamin D.
  • A small serving (85 g) of salmon has 530 IU.
  • Shrimp, mackerel, sardines and fresh herring also are rich in vitamin D.
  • Vitamin D is added to some foods, including tofu, orange juice, and some dairy products.

Eat breakfast. Two eggs, a glass of orange juice (not from concentrate) and a bowl of cereal with milk can add about 300 IU of vitamin D a day.

Talk to your doctor about supplements. If you don’t get much sun and your diet is low in vitamin D, a supplement may help.

Do not take more than 4,000 IU of vitamin D a day unless your doctor has advised you to do so. Too much vitamin D can be toxic and can damage your kidneys.