A Vitamin D 25-Hydroxy (25-OH) test is the most accurate way to measure how much vitamin D is in your body. This form of vitamin D circulates in your blood and is converted to active vitamin D by your kidneys.
What This Test Measures
25-Hydroxyvitamin D [25(OH)D]:
This test measures both D2 (ergocalciferol, from plant sources and supplements) and D3 (cholecalciferol, from sun exposure and animal sources) combined, giving a total vitamin D level.
Understanding Your Results
• Deficient: Below 20 ng/mL (50 nmol/L)
• Insufficient: 20-29 ng/mL (50-72 nmol/L)
• Sufficient: 30-100 ng/mL (75-250 nmol/L)
• Potentially Harmful: Above 100 ng/mL (250 nmol/L)
Optimal levels are debated, but many experts suggest 40-60 ng/mL for optimal health. Consult your healthcare provider for interpretation.
Who Should Consider This Test
• Those with limited sun exposure (indoor workers, northern climates)
• People with darker skin (melanin reduces vitamin D production)
• Adults over 65 (skin produces less vitamin D with age)
• Individuals with conditions affecting fat absorption (Crohn’s disease, celiac disease, gastric bypass)
• People who are overweight or obese
• Anyone experiencing symptoms of deficiency:
– Bone pain or muscle weakness
– Fatigue
– Depression or mood changes
– Frequent illness or infection
• Those taking vitamin D supplements to monitor levels
Why Vitamin D Matters
Vitamin D plays crucial roles in:
• Calcium absorption and bone health
• Immune system function
• Muscle function
• Mood regulation
• Reducing inflammation
Deficiency is associated with increased risk of osteoporosis, fractures, certain cancers, autoimmune diseases, cardiovascular disease, and depression.
How It Works
1. Order your test online – no doctor visit required
2. Visit any Quest Diagnostics location nationwide
3. Simple blood draw takes approximately 5 minutes
4. Results delivered to your secure portal within 1-2 business days
Preparation
No fasting required.
Why Choose Wittmer Rejuvenation Clinic
At $33, our Vitamin D test is significantly less than typical hospital charges ($50-$150+). We partner with Quest Diagnostics for reliable, CLIA-certified laboratory testing with convenient locations across all 50 states.




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