25-Hydroxyvitamin D (25(OH)D) Serum
This test measures the amount of vitamin D in your blood after it has been processed by your liver. Vitamin D helps your body absorb calcium and supports bone health.
["Vitamin D levels help assess your risk for bone-related conditions and overall health."]
Key facts at a glance
- LOINC
- 60493-4
- Short code
- VITDMS
- Synonyms
- Calcidiol+Calciferol SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum separator tube (SST) or gold-top tube; alternatively lithium heparin plasma separator tube (green-top PST)
- Units
- N/A
- Ref low
- 75
- Ref high
- 250
- Critical range
- 25 N/A – 375 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82306
- SNOMED
- 395121001
- Specimen volume
- 1.0 mL serum or plasma (minimum 0.5 mL)
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 6 months; protect from light
- Hemolysis max
- 100
- Lipemia max
- 150
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Doctors may order a 25-hydroxyvitamin D test to check if you have enough vitamin D in your blood. This can be important if you have symptoms like muscle weakness, bone pain, or if you’re at higher risk for conditions like osteoporosis or rickets. It may also be used to monitor vitamin D levels if you’re taking supplements or have certain medical conditions that affect vitamin D metabolism.
How the Test Works
A blood sample is taken from a vein in your arm. The sample is sent to a lab where it is analyzed to measure the concentration of 25-hydroxyvitamin D, a form of vitamin D that reflects your overall vitamin D status.
What to Expect Before the Test
No special preparation is usually needed for this test. However, if you’re taking vitamin D supplements, your doctor may advise you to stop them for a few days before the test to get an accurate reading.
What the Results Mean
Results are typically reported in nanograms per milliliter (ng/mL) or picomoles per liter (pmol/L). Your doctor will interpret the results in relation to your overall health and any symptoms you may have.
Reference range
Calcidiol (25-hydroxyvitamin D): 30-100 ng/mL; Calciferol (vitamin D2): varies based on supplementation status; combined reporting per laboratory protocolN/A
No fasting required. Patient should be well-hydrated. Recent vitamin D supplementation should be documented as it affects calciferol levels.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Vitamin D Level (Serum)
Frequently asked questions
Low levels of 25-hydroxyvitamin D can indicate vitamin D deficiency, which may lead to weakened bones, muscle pain, or increased risk of certain diseases like osteoporosis or certain cancers. High levels might suggest over-supplementation or other underlying conditions. Regular monitoring is important for people with chronic illnesses, those who spend little time outdoors, or those who have conditions affecting vitamin D absorption.
A low vitamin D level may mean your body isn’t getting enough vitamin D from sunlight, diet, or supplements. It can lead to health issues like bone problems or weakened immunity. Your doctor may recommend increasing sun exposure, dietary changes, or supplements to improve your levels.
Test results are usually available within a few days to a week, depending on your lab’s processing time. Your doctor will contact you once the results are ready to discuss them with you.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy