Quick Facts
- Sample: Dried blood spot from finger-prick collected on filter paper card
- Fasting: Not required; collect anytime and note any vitamin D supplements
- Turn-around: Results typically 3-7 business days of lab receipt.
Benefits
- Check vitamin D levels without visiting a clinic or phlebotomist
- Use gold-standard LC-MS/MS method trusted by reference laboratories
- Sample stable at room temperature for over one month during shipping
- Get results you can share electronically with your healthcare provider
- Understand your supplementation response with accurate, clinical-grade testing
Who Is This Test For?
- Adults with limited sun exposure or darker skin tones
- People concerned about bone health, fractures, or falls
- Anyone taking vitamin D supplements wanting to verify adequate dosing
- Individuals with obesity, malabsorption, or chronic kidney or liver disease
- Older adults and those with immune or cardiometabolic health goals
How It Works – Just 3 Steps
- Collect: Warm your hands, prick your finger using the provided lancet, and completely fill the marked circles on the filter paper card with blood drops. Let dry flat for several hours as instructed.
- Mail: Complete the requisition form, seal your dried sample in the protective pouch, and mail using the designated shipping method. Room-temperature stability means no special handling is needed.
- Review: Within 3-7 business days, receive your results showing 25-hydroxyvitamin D2, D3, and total vitamin D, along with reference ranges.
FAQ
What exactly does this test measure? This test measures total 25-hydroxyvitamin D (the sum of D2 and D3), the standard marker of vitamin D status in your blood. It reflects your body's vitamin D stores and readiness for bone health, immune function, and overall wellness.
Is a finger-prick sample as accurate as a regular blood draw? Yes. Dried blood spot results by LC-MS/MS correlate closely with serum samples and are standardized using NIST reference materials, making them suitable for clinical decisions when collected correctly.
How long does it take to get results? Results are typically available within 3-7 business days after the laboratory receives your sample, depending on your ordering platform and lab processing schedules.
What vitamin D levels are considered healthy? Levels below roughly 30 ng/mL are often seen as deficient or insufficient. Most experts recommend levels of 30 to 50 ng/mL or higher for optimal health, though your clinician should interpret your specific result.
Do I need to fast or avoid supplements before testing? Fasting is not required. You can collect your sample anytime and at any time of day. Simply note all vitamin D supplements and dosages on your requisition form for context.
What if my results are high? Persistently elevated levels (above 50-60 ng/mL) may warrant dose reduction or evaluation for excessive supplementation. Discuss results with your healthcare provider for personalized guidance.
More Details
What is the purpose of this test?
This test measures circulating 25-hydroxyvitamin D, the primary indicator of vitamin D status in your body. Results help identify deficiency or insufficiency, monitor your response to supplementation, and guide decisions about bone health, immune function, and disease prevention. The LC-MS/MS method provides the clinical-grade accuracy used by CDC reference laboratories.
What biomarkers are measured in this test?
- 25-Hydroxyvitamin D2 (25[OH]D2)
- 25-Hydroxyvitamin D3 (25[OH]D3)
- Total 25-Hydroxyvitamin D (sum of D2 + D3)
Who would benefit from this test?
Adults with limited sun exposure, darker skin, obesity, malabsorption conditions, or chronic illness benefit greatly from testing. Individuals aged 50 and older, those on long-term supplementation, and anyone with bone health, fall prevention, or immune system concerns are ideal candidates. Regular monitoring is especially valuable for people with bariatric surgery, kidney disease, or liver disease.
When should I order this test?
Consider testing if you have risk factors for deficiency, experience bone pain or frequent infections, or are starting or changing vitamin D supplements. Repeat testing after 3 to 6 months of supplementation changes helps confirm your dose is adequate. Regular annual or biennial screening is reasonable for high-risk individuals.
How do I interpret the results?
Your report will show concentrations of 25-hydroxyvitamin D2, D3, and total vitamin D, along with a reference range
- Below 30–32 ng/mL: Commonly interpreted as deficient or insufficient
- 30–50 ng/mL or higher: Generally considered sufficient
Results should be interpreted in context of age, medical history, medications, and fracture or fall risk
Always review results with a healthcare professional for proper interpretation
Vitamin D deficiency in U.S. adults is associated with a 38% higher risk of all-cause mortality during follow-up, underscoring the importance of adequate levels (Frontiers in Nutrition, 2023).
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.
Pre-test preparation
Wash and dry your hands thoroughly, then warm them gently to improve blood flow. Prick the side of a fingertip using the provided lancet, allow blood drops to form, and completely fill all marked circles on the filter paper card without smearing or layering. Let the card air-dry flat for the time specified in your kit instructions (usually several hours) before placing it in the protective pouch. Maintain your usual medications and supplements unless your provider advises otherwise.
How often should I get tested?
Initial screening:
- Once, if you have risk factors or symptoms
Monitoring supplementation:
- After 3–6 months of starting or changing doses
Ongoing management:
- Every 1–2 years for those on long-term supplementation or with malabsorption conditions
High-risk individuals:
- Annual testing if you have limited sun exposure, obesity, chronic kidney disease, or are aged 65+
Why early detection matters
Vitamin D deficiency is linked to osteoporosis, fractures, falls, and immune dysfunction, contributing substantially to healthcare costs and disability in older adults. About 20-25% of U.S. adults are deficient. Early detection enables timely supplementation and lifestyle changes, preventing bone loss, reducing fracture risk, and supporting overall immune and cardiometabolic health. Routine monitoring of supplementation ensures you achieve target levels safely.
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