Interpret Your Vitamin D (25-OH) Results
Enter your 25(OH)D value below and get an instant, free AI interpretation — a plain-English explanation checked against WHO/IFCC reference ranges.
Medical Disclaimer
This AI-generated interpretation is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Results may vary based on individual health factors not captured here.
Always consult a qualified healthcare professional before making any health decisions. Read full disclaimer →
Vitamin D (25-OH) Normal Ranges
25-hydroxy Vitamin D (calcidiol) is the storage form of vitamin D and the best test to measure overall vitamin D status.
| Reference Range | Unit | Notes |
|---|---|---|
| 30 – 100 | ng/mL | Sufficient |
| 20 – 29 | ng/mL | Insufficient |
Also reported in: nmol/L.Conversion factor: 1 nmol/L = 2.500 ng/mL.
Critical (Panic) Values
Critical Low: < 10 ng/mL. Critical High: > 150 ng/mL. Values outside these limits require immediate clinical attention.
Why Doctors Order the Vitamin D (25-OH) Test
Vitamin D deficiency is a global pandemic affecting over 1 billion people. It is the direct cause of rickets in children and osteomalacia in adults, and a contributing factor to osteoporosis.
How to Enter Your 25(OH)D Result
Vitamin D (25-OH) can be reported in ng/mL or nmol/L. Choose the unit printed next to your result on the lab report so it is compared with the matching reference range.
What a Low or High 25(OH)D Can Be Associated With
Below the reference range
- Insufficient sun exposure (indoor lifestyle, dark skin, living at high latitudes)
- Dietary deficiency (vegans, low dairy intake)
- Malabsorption syndromes (celiac disease, Crohn's disease, gastric bypass)
- Chronic kidney disease (impaired vitamin D activation)
- Liver disease (impaired 25-hydroxylation)
Above the reference range
- Vitamin D toxicity from excessive supplementation (most common)
- Granulomatous diseases (sarcoidosis, TB, histoplasmosis — produce active vitamin D)
- Williams syndrome (genetic hypersensitivity)
This interpreter flags a result at or below 10 ng/mL or at or above 150 ng/mL as a critical value. Results that extreme are uncommon — contact your doctor promptly, and seek urgent medical care if you feel unwell.
These are common associations, not a diagnosis. A single result is read alongside your symptoms, history and other tests — discuss it with your doctor.
What Can Change Your 25(OH)D Result
Before you read too much into a result, consider whether any of these applied:
- Season (significantly lower in winter at high latitudes)
- Skin color (melanin reduces UV-induced vitamin D synthesis)
- Body weight (obesity sequesters vitamin D, lowering levels)
- Sunscreen (blocks UV-B synthesis if applied consistently)
Preparing for the test: No fasting required. For accurate results, no vitamin D supplements for 24 hours before testing (although most labs measure steady-state 25-OH D, which changes slowly).
Symptoms That Often Prompt 25(OH)D Testing
- Bone pain and tenderness
- Muscle weakness and frequent falls
- Fatigue and general malaise
- Depression
- Frequent infections (reduced immunity)
Want the full clinical guide to Vitamin D (25-OH)?
Reference ranges, causes, symptoms, preparation, and FAQs.