Quick Facts
- Sample: Blood
- Fasting: No special preparation is required
- Turnaround: 4-10 days. May take longer based on weather, holiday, or lab delays.
What This Test Measures
This test measures total Vitamin D, 25-hydroxy, along with its two fractionated forms, Vitamin D2 (25-hydroxy) and Vitamin D3 (25-hydroxy), in the blood. Vitamin D2 (ergocalciferol) primarily comes from plant sources and fortified foods or supplements, while Vitamin D3 (cholecalciferol) primarily comes from animal products, sun exposure, and supplements. Reporting both forms separately, in addition to the total, allows each fraction to be viewed individually rather than only as a combined value.
This test uses LC/MS-MS (liquid chromatography with tandem mass spectrometry) methodology to measure these biomarkers. The three biomarkers tested are 25-Hydroxy Vitamin D, 25-Hydroxy Vitamin D-2, and 25-Hydroxy Vitamin D-3.
Benefits
- Reports total Vitamin D along with the D2 and D3 fractions
- Distinguishes plant derived D2 from animal derived and sun derived D3
- Uses LC/MS-MS methodology for fractionated reporting
- Requires no special preparation before testing
- Provides results a healthcare provider can help interpret
- Supports ongoing monitoring alongside professional guidance
Who Is This Test For?
- People whose provider wants to see D2 and D3 levels separately
- People tracking vitamin D related bone or joint discomfort
- People with limited sun exposure or consistent sunscreen use
- People with darker skin pigmentation and reduced natural D3 synthesis
- People with conditions affecting nutrient absorption, such as celiac or Crohn's disease
- People being monitored while using vitamin D2 or D3 supplements
How It Works
- Order Your Test Online
- Visit a Local Lab
- Get Results Online
FAQ
1. What is the purpose of this test?
This test measures total circulating 25-hydroxy Vitamin D and its two fractionated forms, D2 and D3, using LC/MS-MS methodology. It can help a healthcare provider evaluate your current vitamin D status by looking at each form separately rather than only a combined total. This test does not, by itself, diagnose a vitamin D deficiency or toxicity.
2. Who would benefit from this test?
People interested in seeing their vitamin D2 and D3 levels reported separately, rather than as a single combined number, may benefit from this test. It may also be useful for people with limited sun exposure, darker skin pigmentation, or conditions that affect nutrient absorption. A healthcare provider can help determine if this test fits your situation.
3. When should I order this test?
You may consider this test if you have experienced bone or joint pain, muscle weakness or aches, or signs of low bone density. It may also be considered if you have limited sun exposure, a history of weight loss surgery, kidney or liver disease, or a condition that affects nutrient absorption. This test does not replace a broader medical or nutritional evaluation.
4. How does this test differ from other nutritional tests?
This is a blood test that reports total 25-hydroxy Vitamin D along with its D2 and D3 fractions, measured using LC/MS-MS methodology. A traditional Vitamin D 25-Hydroxy test reports only the total value without breaking it into D2 and D3 fractions. Because this test uses a blood specimen, its results are not interchangeable with any urine based nutritional measurement.
5. Do I need to fast before this test?
No special preparation is required for this test.
6. How quickly will I get results?
Results are typically available in 4-10 days. Results may take longer based on weather, holidays, or lab delays.
7. How do I interpret the results?
The meaning of your total, D2, and D3 results depends on your individual health history, symptoms, diet, supplement use, medications, and other laboratory findings. A low result does not automatically confirm a deficiency, and a normal result does not automatically rule out a nutritional concern. Your provider may consider these results alongside other laboratory findings for a fuller picture.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
8. What should I do if my results are abnormal?
If your results fall outside the expected range, review them with a qualified healthcare provider. They can help determine what the result means for you and whether any additional evaluation or testing is appropriate. This test result alone does not provide a complete clinical conclusion.
9. How often should I get tested?
Testing frequency should be determined as directed by your healthcare provider based on your individual health needs and history. There is no set schedule for this test, and your provider can help decide what makes sense for your situation.
Pre test preparation
No special preparation is required.
