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.
Many people can get the amount of vitamin D needed each day through food and sunlight.
The vitamin D test is also called the 25-hydroxy vitamin D, or 25(OH)D, test.
You may need this test if you:
There is nothing to do to prepare for this test.
Your health professional drawing blood will:
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having a blood sample taken from a vein.
A vitamin D test measures the amount of vitamin D in the blood.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
30–80 nanograms per milliliter (ng/mL)
High levels of vitamin D can be caused by:
Low levels of vitamin D can be caused by:
Medicines that may decrease vitamin D levels include:
Pagana KD, Pagana TJ (2011). Vitamin D (25-hydroxy vitamin D). In Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed., pp. 543–547. St. Louis: Mosby.
June 14, 2013
E. Gregory Thompson, MD - Internal Medicine
& Kathleen Romito, MD - Family Medicine
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