Which deficiencies does a blood test cover?
The four deficiencies that are most common and cause the most complaints: vitamin D (bones, muscles, immune system), vitamin B12 (red blood cells and the nervous system), folate (cell division and blood production) and iron, strictly a mineral, measured through ferritin (your iron stores).
All four are part of the comprehensive test by default. No need to pick which deficiency to test: you measure them together, in the same blood test of 52 values.
Why symptoms mislead
A vitamin D deficiency, a B12 deficiency and an iron deficiency produce largely the same complaints: fatigue, low energy, poor concentration. Without measuring there is no telling which deficiency is at play, or whether there is no deficiency at all and the cause lies elsewhere.
Supplementing blindly does not solve that. Supplement the wrong thing and the complaints stay; and for some nutrients, like iron, too much is actively harmful. Measure first, then supplement with purpose.
From result to plan
For every value the app shows the lab's reference range, where you stand and what that means. With a confirmed deficiency you supplement through food or a targeted supplement, and when your B12 status is unclear, the True vitamin B12 add-on (with MMA) settles whether a low B12 is a true functional deficiency.
Re-test after 8 to 12 weeks to see the deficiency recover. For strongly abnormal values we advise contacting your doctor; the result shares easily as an attachment.
Want to know which deficiency is real? Measure vitamin D, B12, folate and your iron status in one blood test.
Test your blood valuesThe biomarkers behind each deficiency
For each deficiency we measure more than one value, so you also see whether a shortage already shows in your blood picture:
Beyond the comprehensive test, targeted add-ons let you go deeper into a specific marker or system.
How to test for a vitamin deficiency
Order the comprehensive test
Rather measure every year?
Book your draw in the app
See which deficiency is at play
Supplement with purpose and re-test
Frequently asked questions
The key questions about testing for vitamin deficiencies.
Through a blood test. With Optimize you order it yourself, no doctor's referral needed. Vitamin D, vitamin B12, folate and your iron status (ferritin) are part of the comprehensive test by default.
Take control.
Comprehensive test
One draw at a location near you, results explained in the app.
- 52 blood values in one draw
- Results within 24 hours, in plain language
- No referral, no waiting list
- 600+ draw locations in the Netherlands
- Your trends on every retest, in the app
No referral needed · Results within 24 hours
Rather measure continuously? Core membership (€1 a day)