Vitamin D Test

Why this test may be ordered

• To check for vitamin D deficiency if you have a condition such as osteomalacia, low bone density, osteoporosis, or rickets.
• If you have symptoms like bone pain, muscle weakness or aches, soft or deformed bones, or weak bones and fractures.
• If you have a high risk for deficiency due to limited sun exposure, poor diet, malnutrition, weight loss surgery, conditions that affect nutrient absorption (e.g., Crohn's disease, ulcerative colitis, celiac disease), kidney or liver disease, or certain medicines (e.g., statins, steroids, weight-loss medicines).
• For babies mainly fed breastmilk or children with diets low in vitamin D.
• To monitor if vitamin D levels are improving with supplements, or to check for toxicity if you have symptoms of too much vitamin D (nausea, vomiting, poor appetite, constipation, muscle weakness, weight loss).

Preparation and collection

You don't need any special preparations. Tell your provider about all medicines, vitamins, and supplements you take, because they may affect your results. Do not stop taking any medicines unless your provider tells you to.

Blood sample from a vein in your arm.

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

Understanding results

Your test results may be reported as 'total vitamin D,' or as the amounts of vitamin D2 and vitamin D3. Total vitamin D is the important number to check. The results below describe total vitamin D levels.

• Deficient: Very low vitamin D levels that are likely to affect your bones and general health. Limitation: Your test result may be reported as total vitamin D or as separate vitamin D2 and D3 amounts; total vitamin D is the important number to check. Next step: Your provider may recommend vitamin D supplements and/or eating more foods rich in vitamin D. This is usually safer than getting more sun.
• Insufficient: Low vitamin D levels that may weaken your bones and affect your health, even if you don't have symptoms. Limitation: Your test result may be reported as total vitamin D or as separate vitamin D2 and D3 amounts; total vitamin D is the important number to check. Next step: Your provider may recommend vitamin D supplements and/or eating more foods rich in vitamin D. This is usually safer than getting more sun.
• Sufficient or optimal: Vitamin D levels that are enough for good bone and general health for most people. Limitation: Total vitamin D is the important number. Your result may be reported as total vitamin D or as separate vitamin D2 and D3 amounts. Next step: Talk with your provider if you have questions about your result.
• Toxic or possible toxicity: Very high vitamin D levels that might cause health problems. This usually means you're getting too much vitamin D from supplements. Limitation: Your test result may be reported as total vitamin D or as separate vitamin D2 and D3 amounts; total vitamin D is the important number to check. Next step: You'll need to stop taking the supplements to reduce your vitamin D levels, because too much vitamin D can cause serious damage to your organs and blood vessels.

• There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
• Routine vitamin D testing is not recommended for everyone.

What to do next

To learn what your vitamin D test results mean, talk with your provider.

• Why is this test being ordered for me?
• What do my total vitamin D level and the result label (deficient, insufficient, sufficient/optimal, or toxic/possible toxicity) mean for my health?
• If my level is low, what are the recommended ways to increase it safely?
• If my level is high, what steps should I take to lower it?
• How often should I have this test repeated?

Evidence source

Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.

U.S. National Library of Medicine: Vitamin D Test

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