Test Overview
A vitamin D test measures the amount of vitamin D in the blood. Your body needs vitamin D to absorb calcium. Calcium keeps your bones and muscles healthy and strong.
If your muscles don't get enough calcium, they can cramp, hurt, or feel weak. You may have long-term (chronic) muscle aches and pains. If you don't get enough vitamin D throughout life, you are more likely to have thin and brittle bones (osteoporosis) in your later years.
Children who don't get enough vitamin D may not grow as much as others their age. They also have a chance of getting a rare disease called rickets.
Your body uses sunshine to make its own vitamin D. Vitamin D is found in foods such as egg yolks, liver, and saltwater fish. It is added to many food products, such as milk, orange juices, yogurts, margarines, and soy beverages. You can also get it as supplements, often combined with calcium.
Health Canada and Osteoporosis Canada recommend that Canadian adults take daily vitamin D supplements.
The vitamin D test is also called the 25-hydroxy vitamin D, or 25(OH)D, test.
Why It Is Done
In Alberta, you can only get this blood test if you have a medical condition that could be affected by low levels of vitamin D. This includes medical conditions such as:
- Blood calcium levels that are too high or too low.
- Bone diseases (such as osteoporosis or Paget’s disease).
- Problems absorbing nutrients (such as celiac disease, small intestine surgery, taking medicines for seizures).
- Chronic (long-term) kidney or liver disease.
Most healthy Albertans don’t need a vitamin D test. Vitamin D test results likely won’t change the advice from your healthcare provider. What’s important is that you try to get enough vitamin D from the sun, foods, and supplements.
To learn more about vitamin D supplements and other sources of vitamin D, talk to your healthcare provider or see:
How To Prepare
In general, there's nothing you have to do before this test, unless your doctor tells you to.
How It Is Done
A health professional uses a needle to take a blood sample, usually from the arm.
Watch
How It Feels
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
Risks
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Results
Normal
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
High values
High levels of vitamin D can be caused by:
- Williams syndrome. This is a genetic problem that causes growth delays before and after birth.
- Taking too many vitamin D supplements.
Low values
Low levels of vitamin D can be caused by:
- Kidney disease.
- Liver disease.
- Not getting enough sunlight.
- Not getting enough vitamin D in your diet.
Credits
Adaptation Date: 12/12/2023
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
