Vitamin D
Disclaimer: Information on this page is for educational purposes. Consult a physician to interpret your test results. Health Vault helps track biomarker trends but does not replace medical advice.
What This Test Measures
25-OH vitamin D is the best marker of vitamin D status. Critical for calcium absorption and bone health.
<20 ng/mL — deficiency; 20–30 — insufficiency; >100 — potential toxicity.
Normal Ranges
| Group | Reference Range |
|---|---|
| Men | 30–100 ng/mL (75–250 nmol/L) |
| Women | 30–100 ng/mL |
| Children | 30–100 ng/mL |
Reference ranges may vary by laboratory and assay method.
Causes of High Levels
- Excess supplementation
- Sarcoidosis
- Lymphoma
Causes of Low Levels
- Insufficient sun exposure
- Malabsorption
- Obesity
- Chronic kidney disease
Test Preparation
- No special preparation
- Report vitamin D supplements
Related Biomarkers
| Biomarker | Relationship |
|---|---|
| Calcium | Bone-mineral axis |
| Phosphorus | Mineral metabolism |
| Alkaline Phosphatase | Bone turnover |
FAQ
How often should I take this test?
With osteoporosis — baseline + after 3 months.
What should I do if my result is abnormal?
Deficiency — supplement; toxicity — stop supplements and check calcium.
Last updated: June 2026