Vitamin D (25-OH-D)
Diagnostics · Vitamin D status
Tier A
What this is
Variable by geography/season/skin pigmentation. Don't confuse 25-OH-D (what you want) with 1,25-OH-D (only order for specific endocrine/kidney indications). Levels >100 ng/mL should prompt dose reduction — no benefit and theoretical risk of hypercalcemia with sustained very high levels.
Mechanism
25-hydroxyvitamin D is the storage form and best indicator of vitamin D status; 1,25-(OH)2-D (active form) is tightly regulated and not useful for status assessment
Dose & route
Annually; target 40-60 ng/mL (biohacker consensus); mainstream cutoff 20-30 ng/mL
Citations
- https://pubmed.ncbi.nlm.nih.gov/21646368/
- https://pubmed.ncbi.nlm.nih.gov/30541089/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6213953/
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This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.