Patient education: Vitamin D blood test (The Basics)

What is a vitamin D blood test? — 

This is a test to check the level of vitamin D in the blood. The body needs vitamin D to absorb calcium and keep bones strong.

Foods with a lot of vitamin D include milk, canned tuna fish, cod liver oil, yogurt, ready-to-eat-cereals, salmon, canned sardines, mackerel, and eggs. The body can also make vitamin D when exposed to sunlight.

When a person does not have enough vitamin D, it is called "vitamin D deficiency."

Why might I get a vitamin D blood test? — 

Your doctor might order this test if you are at risk for vitamin D deficiency. This might be the case if you:

●Spend most or all your time indoors

●Have medical problems (such as celiac disease) that make it hard for you to absorb vitamin D

●Have a condition called "osteoporosis," which makes bones break easily

How do I prepare for a vitamin D blood test? — 

You need to get a "blood draw." Your doctor or nurse will tell you where to go for this.

It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.

What happens during a blood draw? — 

A needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

Tell the person who takes your blood:

●If you take "blood thinner" medicines or have a bleeding problem – They will make sure your bleeding is under control before you leave.

●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

●If you have a preferred arm to use

Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.

What do my results mean? — 

Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

If your vitamin D level is low, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out the cause. They might recommend taking vitamin D supplements.

If you do have a health problem, your doctor will work with you to come up with a treatment plan.

More on this topic

Patient education: Vitamin D deficiency (The Basics)
Patient education: Calcium and vitamin D for bone health (The Basics)
Patient education: Vitamin D for babies and children (The Basics)
Patient education: Osteoporosis and osteopenia (low bone mass) (The Basics)
Patient education: Hypocalcemia (The Basics)
Patient education: Vitamin supplements (The Basics)

Patient education: Vitamin D deficiency (Beyond the Basics)
Patient education: Calcium and vitamin D for bone health (Beyond the Basics)
Patient education: Osteoporosis and osteopenia (low bone mass) (The Basics)