Nutrient · Hormonal vitamin
Men Women (soon)
Vitamin D 25(OH)(Vit D)
Vitamin D is more hormone than vitamin. Optimal status influences testosterone production, immune regulation, mood, and bone density.
Optimal range
50–80ng/mL
Clinical "normal"
30–100 ng/mL
Avg. cost (US)
$45
Test frequency
Annually (twice if dosing aggressively)
When to measure
Any time of day, fasted not required.
How to measure
25-hydroxyvitamin D total — standard immunoassay or LC-MS/MS. The active form (1,25-OH) is rarely needed.
Average cost
≈ $45 cash price. Often covered by insurance with relevant ICD-10.
Signs your level is off
Symptoms if low
Immune weakness, depression.
Symptoms if high
Hypercalcemia.
If your level is low
>10k IU: toxicity
Supplement
Vitamin D3· 2000-5000 IU/day
Form: Cholecalciferol
Bone and immune support.
Foods
- Fatty fish
Lifestyle
- Sun 20 min/day
Medication (if prescribed)
Calcifediol· 0.266 mg/week
Form: Oral
Reference only. Speak with a licensed clinician before any prescription intervention.
Caution: >10k IU: toxicity
If your level is high
N/A
Foods
- Low-vitamin D diet
Lifestyle
- Balanced diet
Medication (if prescribed)
IV fluids· As needed
Form: IV
Reference only. Speak with a licensed clinician before any prescription intervention.
Test these together
These biomarkers contextualize Vitamin D 25(OH) and unlock a clearer picture than any single value can.
Protocols that move this marker
Selected studies
VITAL 2025 NEJM
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