How is vitamin D deficiency diagnosed?

Dr. Robin Miller, MD
Internal Medicine
Vitamin D deficiency can be diagnosed with a simple blood test. Laboratories vary on what they consider to be deficient. I like for my patients’ blood levels of vitamin D to be between 40 ad 80 ng/ml.
A doctor may use blood tests, x-rays, physical examination and medical history to diagnose someone with vitamin D deficiency. Blood tests measure the levels of a particular form of vitamin D called 25-hydroxyvitamin D, or 25(OH)D for short. According to the Institute of Medicine, people are deficient if they have less than 12 nanograms per milliliter (ng/mL) of 25(OH)D in their blood.

People with levels of 12 to 20 ng/mL are considered "at risk" for vitamin D deficiency. Symptoms such as bowlegs or knock-knees in children, and thinning bone as measured by bone density tests and x-rays, are other factors that might prompt a doctor to consider a diagnosis of vitamin D deficiency. A doctor may also suspect vitamin D deficiency if he or she knows that a person doesn't get enough exposure to sunlight or has a poor diet. Talk to your doctor if you think you might be at risk for vitamin D deficiency.

Continue Learning about Vitamin D

Jump-start Your Well-being with Vitamin D
Jump-start Your Well-being with Vitamin D
Turns out, vitamin D has more power to protect your happiness, heart and lungs than was previously known. A study in the European Journal of Preventi...
Read More
How can I get enough vitamin D?
David Slovik, MDDavid Slovik, MD
Vitamin D is made in the skin after exposure to sunlight. Some people make all the vitamin D the...
More Answers
What are some causes of a vitamin D deficiency?
Univ. of Nev. School of Medicine, Family MedicineUniv. of Nev. School of Medicine, Family Medicine
When it comes to Vitamin D deficiency, I always tell my patients the two most important ways to ...
More Answers
Can I Get Enough Vitamin D Through Exposure to Sunlight?
Can I Get Enough Vitamin D Through Exposure to Sunlight?

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.