Ajax Harwood Clinic

Vitamin D level (25-OH)

Full name: Vitamin D, 25-hydroxy (25-OH vitamin D)

This test is useful only in specific situations — it's not right for everyone who asks about it.

What this test is

Vitamin D helps build strong bones. Low vitamin D is common in Canada, especially in winter. But most healthy adults do not need a blood test for it. A 2024 expert guideline advises against routine testing, because the result usually does not change the advice. A test does make sense in some cases. These include weak bones (osteoporosis or osteopenia), a gut problem that affects absorption, kidney disease, or a medicine that changes how your body uses vitamin D. If one of these fits you, your doctor can order it, and it is covered by OHIP. If not, ask your doctor what amount of vitamin D from food or a supplement is right for you.

Want to see the full clinical reasoning? The reference we use for this test is open to anyone — it is detailed and written for clinicians, and you are welcome to read it.

Open the clinician reference →

Looking for other tests, or more on a condition an ND raised? Explore ask.ajaxharwoodclinic.com →

General health information for Ajax Harwood Clinic patients and the public — not medical advice, and not a substitute for seeing your own doctor. Last reviewed 2026-09-23.