Vitamin D Blood Test
Every cell in your body has vitamin D receptors, highlighting how vital this nutrient is to overall health. Your body synthesises vitamin D from sunlight, yet people living in the northern hemisphere rarely get enough from sun exposure alone. Even those in warmer climates are frequently deficient. Optimal vitamin D levels are linked to better bone density, stronger immune function and reduced risk of several chronic diseases. A simple blood test measuring 25-hydroxyvitamin D reveals your current status.
Why Test Vitamin D?
Testing is recommended if you live in a northern climate, have limited sun exposure, have dark skin, cover up outdoors, are over 50, are pregnant, or take medications such as corticosteroids or antacids that affect vitamin D metabolism. It is also useful for monitoring supplementation progress and for those with genetic variants that impair vitamin D absorption.
What Do High Vitamin D Levels Mean?
Very high vitamin D levels, typically above 250 nmol/L, may indicate toxicity, most often from excessive supplementation. Rarely, conditions such as sarcoidosis can elevate levels. Symptoms include nausea, vomiting, weakness and kidney problems. The optimal range is generally 75 to 150 nmol/L.
What Do Low Vitamin D Levels Mean?
Low vitamin D means your body is not producing or absorbing enough of the vitamin. Deficiency is defined as levels below 50 nmol/L, and insufficiency as 50 to 75 nmol/L. Causes include limited sun exposure, dark skin, obesity, malabsorption conditions (celiac disease, IBD), liver or kidney disease, and certain medications. Severe deficiency causes rickets in children and osteomalacia in adults.
Symptoms to Watch For
- Bone pain and muscle weakness
- Fatigue and general tiredness
- Frequent infections or slow wound healing
- Low mood or depression, especially in winter
- Hair loss
- Back and joint pain
Who Should Get Tested?
- People living in northern latitudes with limited sun exposure
- Those with dark skin or who cover up outdoors
- Adults aged 50 and over
- Pregnant or breastfeeding women
- People with celiac disease, IBD or other malabsorption conditions
- Those taking corticosteroids, antacids or anti-seizure medications
- Individuals with osteoporosis or frequent bone fractures
How to Prepare for Your Test
No fasting or special preparation is needed. Bring valid ID to the lab. If you take a supplement containing biotin (often sold for hair and nails), pause it for two days before the test, as high doses can distort the result.
Order Your Blood Test
Test your Vitamin D levels with an accredited Swedish laboratory. Results within days, reviewed by Wellth.
Frequently Asked Questions
What is an optimal vitamin D level?
Can I get enough vitamin D from food alone?
How much vitamin D should I supplement?
Should I also take vitamin K2 with vitamin D?
Reviewed by
Wellth Team
Wellth
Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.
Learn more about our team →Medical Disclaimer
The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.