Vitamin D (25-hydroxyvitamin D) Blood Test
Vitamin D is the most-tested nutrient in Australia — and one of the most commonly low, even with our climate.
What Vitamin D measures
The 25-hydroxyvitamin D blood test (also called 25-OH-D) measures the form of vitamin D circulating in your blood. It's the standard marker of your vitamin D status — the calcidiol form your liver makes from sunlight exposure and dietary vitamin D, before it's converted into the hormonally active form.
Who should consider checking Vitamin D
Have you noticed any of these:
- mostly indoor work and limited sun exposure
- diligent sunscreen use year-round
- darker skin (which makes less vitamin D from the same sun exposure)
- older adult or after pregnancy
- frequent colds or low immunity
- muscle aches or fatigue without obvious cause
How the test works
Single blood draw, no fasting required. Results back same day.
What "normal" can look like
Australian labs commonly use a reference range starting around 50 nmol/L for sufficiency, but optimal-functioning levels are often discussed at the higher end of normal. Vitamin D shifts seasonally — testing in late winter typically gives the lowest reading; late summer the highest. Discuss any deficiency or starting supplementation with your doctor.
Where to get a Vitamin D test
Vitamin D is included in these panels:
- Vitamin & Mineral Panel — The essential nutrients behind energy, immunity and bone health — checked in one test. A$249
- Core Health Panel — The full check — 42 biomarkers across 8 health areas, in one blood test. Our most comprehensive panel. A$329
Frequently asked questions
Why test if I'm in Australia?
Sun avoidance, sunscreen, indoor work and skin pigmentation all reduce vitamin D production. Australia actually has surprisingly high rates of vitamin D insufficiency — testing tells you where you actually sit.
Should I fast?
No fasting required.
How often should I test?
Once a year is enough for most people. After starting supplementation, test 8–12 weeks in to see whether you're responding.
Can vitamin D be too high?
Yes — usually only with high-dose supplementation. The test can flag this before it becomes a problem.
Related biomarkers
Guides
- Can You Get a Blood Test in Australia Without a GP Referral? (2026) — Yes — most common blood tests can be self-ordered in Australia. How direct-to-consumer pathology works, what's available, and when you should still see a GP first.
- How Much Does a Private Blood Test Cost in Australia? A Buyer's Guide (2026) — Private blood tests in Australia range from $35 for single biomarkers up to $500+ for comprehensive panels. What you're paying for, what drives the cost, and when private testing is worth it.