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Nutrient Status · Marker 02

25(OH)D · Vitamin D, 25-hydroxy

Vitamin D is what your skin makes from sunlight, and what your body stores. We measure the storage form.

Educational, never diagnosticReviewed Apr 14, 2026

Common reference range

40–60 ng/mL

Worth watching
Above 80 ng/mL
Population median
28 ng/mL
Units
ng/mL

Your record always keeps the range printed on the report the result came from, which can differ from the range above.

Why it matters

What 25(OH)D tells you.

Most people in northern climates run low for half the year. Low vitamin D affects energy, mood, immunity, and recovery.

25-hydroxyvitamin D is the precursor to the active hormone 1,25-(OH)₂D. Measuring it gives a stable picture of your body's reserve.

Optimal sits in a narrow window. Both deficiency and excess have downsides; we hold members between 40 and 60 ng/mL.

What the record reads

The direction, not one number.

Whether you stay between 40 and 60 ng/mL across seasons, summer and winter.

25(OH)D · ng/mL · six results

Illustrative series

Once you file two results, the record compares them to each other rather than to a population average, and names the report each value came from.

What can influence it

The things that move 25(OH)D.

In rough order of effect, and read alongside your own history rather than on their own.

  1. 01

    Sun exposure

    Latitude-dependent. Northern winters require supplementation.

  2. 02

    D3 supplementation

    Generally 2,000, 5,000 IU/day, titrated to range.

  3. 03

    Body composition

    D is fat-soluble; higher fat mass requires higher intake to achieve the same level.

  4. 04

    Magnesium status

    Required cofactor for D activation.

Daily things that show up here

  • Get 15, 20 minutes of midday sun when possible
  • Supplement D3 in winter (2,000, 5,000 IU)
  • Take with a meal containing fat
  • Re-test after three months

In your record

What happens when a 25(OH)D result arrives.

The same four steps for every result, whether you upload a report or type a value in by hand.

  1. 01

    Filed to its date

    The value is stored against the day it was drawn, with the report it came from kept alongside it.

  2. 02

    Named and normalized

    Vitamin D, 25-hydroxy is recognised as one measure, so the same marker from two labs joins one series.

  3. 03

    Read in plain language

    You see what it measures, whether it sits in the printed range, and what usually moves it.

  4. 04

    Shared only if you say so

    A clinician sees this result when you grant scoped, expiring access, and the view is logged.

This page is educational. It does not diagnose, and it does not replace a conversation with a clinician who can see your history.

Where to go next

  • Start with one report

    Upload a single lab report and 25(OH)D is filed to its date, named and read back in plain language.

    Create my free record

  • Find someone to read it with

    The directory opens filtered to clinicians who work with nutrient status markers.

    Verified clinicians

  • Read the evidence

    The reading list opens searched for 25(OH)D, with every study linked back to its source.

    Studies on 25(OH)D

Read alongside

Other nutrient status markers.

References

Where this comes from.

  1. Holick MF. Vitamin D Deficiency. N Engl J Med. 2007;357:266-281. DOI

Reviewed by Dr. Sarah Chen, MD · Last reviewed Apr 14, 2026