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Vitamin D Test
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 and cereals. You can also get it as supplements, often combined with calcium.
The vitamin D test is also called the 25-hydroxy vitamin D, or 25(OH)D, test.
Why It Is Done
You may need this test if you:
- Have low levels of calcium or phosphate.
- Have osteoporosis or low bone density.
- Had a broken bone after a fall from standing, such as if you trip and fall. The break most commonly occurs in the hip or wrist.
- Have gone through menopause and worry about osteoporosis.
- Have low levels of vitamin D.
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.
Related Information
Credits
Current as of: September 8, 2022
Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Kathleen Romito MD - Family Medicine
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Why It Is Done
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How To Prepare
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How It Is Done
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How To Prepare- Top of the page
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How It Feels
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How It Is Done- Top of the page
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Risks
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How It Feels- Top of the page
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Results
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Risks- Top of the page
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Related Information
Previous Section:
Results- Top of the page
Next Section:
Credits
Previous Section:
Related Information- Top of the page
Current as of: September 8, 2022
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine
