BiomarkersVitamin D (25-OH)

Vitamins

Vitamin D (25-OH)

Your body's vitamin D store, for bones, immunity and mood

On your report it may say: 25-OH Vitamin D, 25(OH)D, 25-hydroxy vitamin D

This test measures 25-hydroxyvitamin D, the form your body stores and the best single measure of vitamin D status. Low levels are very common in India despite plenty of sun, because of indoor lifestyles, clothing, sunscreen and darker skin.

Updated 2026-10-26

Typical ranges · ng/mL

Deficient below 20
Insufficient 20–30
Sufficient 30–100
Too high 100+

nmol/L = ng/mL × 2.5

Some experts aim for 40–60 ng/mL. Don't confuse this test with 1,25-dihydroxy vitamin D, which is a different test.

Ranges vary by lab, age and sex. The range printed on your report applies.

If it's low

Your stores are running low, which over time can weaken bones and may affect muscles, immunity and mood.

Common causes

  • Little time in direct sun
  • Darker skin, covered clothing or regular sunscreen
  • Higher body weight (vitamin D is stored in fat)
  • Gut conditions that reduce fat absorption
  • Some medicines, such as certain anti-seizure drugs and steroids

What you might notice

  • Tiredness
  • Aching bones or muscle weakness
  • Frequent infections
  • Low mood
  • Often no symptoms at all

If it's high

Levels above 100 ng/mL almost always come from high-dose supplements and can raise blood calcium.

Common causes

  • Taking high doses for a long time
  • Doubling up across several products
  • Rarely, certain medical conditions

What you might notice

  • Nausea or poor appetite
  • Thirst and passing more urine
  • Constipation
  • Confusion (with very high calcium)

Testing

Who should test
Anyone with little sun exposure, darker skin, higher body weight, bone health concerns, or who is pregnant or over 60.
How to prepare
No fasting needed. Mention any vitamin D you take.
When to retest
8–12 weeks after starting or changing a dose; then once or twice a year.

What can help

Food sources

Sunlight on bare skinEgg yolksOily fishUV-exposed mushroomsFortified milk

See a doctor if your level is very low with bone pain, or above 100 ng/mL, or if your calcium is also abnormal.

Common questions

Does sitting in sunlight through a window help?

Not much. Glass blocks most of the UVB light skin needs to make vitamin D.

How fast does vitamin D go up?

Most people see a clear rise within 2–3 months of steady daily dosing.

Why test it if I live in a sunny country?

Sun alone doesn't guarantee good levels; deficiency is widespread in India.

Explore further

Sources

  1. MedlinePlus (US National Library of Medicine): Vitamin D test
  2. NIH Office of Dietary Supplements: Vitamin D fact sheet for health professionals

Free nutrition assessment

Not sure what your body needs?

Answer a few questions about your diet, lifestyle and goals, and SYNC builds a personalised supplement plan with the reason for every suggestion. Free, about 6–8 minutes.

Build My Nutrition Plan

For general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.