25ohd325ohd2serplscnc
A blood test that measures the level of 25-hydroxyvitamin D in your blood to assess your vitamin D status.
{"Measures 25-hydroxyvitamin D (25(OH)D), the major form of vitamin D in blood","Helps diagnose vitamin D deficiency or excess","Results reflect both vitamin D2 (plant-based) and vitamin D3 (animal-based) intake","Typically performed on a blood serum sample","Used to monitor bone health, calcium metabolism, and certain chronic conditions"}
Key facts at a glance
- LOINC
- 68438-1
- Short code
- VITD25
- Synonyms
- 25(OH)D3+25(OH)D2 SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST/gold top) or plain red top tube
- Units
- N/A
- Ref low
- 50
- Ref high
- 250
- Critical range
- 25 N/A – 375 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Chemiluminescence Immunoassay (CLIA) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82306
- SNOMED
- 368009
- Specimen volume
- 1.0-2.0 mL of serum
- Stability
- Room temperature: 7 days; Refrigerated (2-8°C): 14 days; Frozen (-20°C or below): 30 days. Protect from light exposure.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 40
- TAT
- 24–72 hours
- Order
- routine
What is this test?
The 25-hydroxyvitamin D test measures the amount of 25-hydroxyvitamin D in your blood serum. This test is considered the best indicator of your body's vitamin D status because 25(OH)D is the major form of vitamin D that circulates in the bloodstream and has a relatively long half-life.
Vitamin D exists in two main forms: vitamin D2 (ergocalciferol, from plant sources and supplements) and vitamin D3 (cholecalciferol, from sunlight exposure, animal foods, and supplements). This test measures both forms together to give a total picture of your vitamin D status.
During the test, a healthcare professional will draw a small sample of blood from a vein in your arm. The sample is then sent to a laboratory for analysis. No special preparation is usually required, though your doctor may ask you to fast for a short period.
Reference range
Deficient: <50 nmol/L; Insufficient: 50-74 nmol/L; Sufficient: 75-250 nmol/L; Toxicity: >250 nmol/LN/A
No special preparation required. Fasting is not mandatory but may be recommended depending on laboratory protocol. Inform the laboratory of any vitamin D supplements or medications that may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings4
Frequently asked questions
What do the results mean?
How often should I have this test?
Do I need to fast before the test?
What can I do to improve my vitamin D levels?
Sources
- 1
- 2Mayo Clinic - Vitamin DSource
- 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 10, 2026. · Read our editorial policy