Vitamin D plays a role in bone strength, muscle function and the immune system. A measurement provides insight into your 25-OH vitamin D level, with personal explanation by our doctors.
Interpreted by BIG-registered doctors
Achtergrond
Vitamin D is a fat-soluble vitamin that the body largely produces itself under the influence of sunlight on the skin. We also obtain a smaller amount from food such as fatty fish, eggs and fortified products. Vitamin D is important for the absorption of calcium and phosphate, and therefore for strong bones and good muscle function. It also plays a role in the functioning of the immune system.
Vitamin D is measured in the blood as 25-hydroxy vitamin D (25-OH-D), expressed in nanomoles per litre (nmol/L). This value reflects the supply over the past weeks to months. In the Netherlands, low values are seen more often in winter months, with limited sun exposure, a darker skin tone, at older age and with obesity.
In het kort
Fat-soluble
Stored in adipose tissue
Sunlight
Primary source via the skin
Bone & muscle
Important for calcium absorption
Seasonal
Lower levels in winter
Veelvoorkomende redenen om te meten
Hieronder enkele situaties waarin een meting van Vitamin D inzicht kan bieden.
A single measurement provides a snapshot of your vitamin D supply, a starting point to understand how your body is doing.
Those who take vitamin D supplements can measure after a few months whether the level has built up to the desired amount.
Vitamin D levels fluctuate with the seasons. A measurement at the end of winter and/or end of summer shows your natural pattern.
People who work mostly indoors, cover up outside or rarely go outdoors statistically more often have a low vitamin D level.
The production of vitamin D in the skin decreases with age, a measurement provides insight into whether supplementation may be useful.
Vitamin D is one of the most measured markers in self-chosen blood testing, as a basic check of your vitamin status.
Wat betekent uw uitslag
Vitamin D is measured as 25-OH vitamin D in nanomoles per litre (nmol/L). The interpretation of your result is performed by our doctors based on the standard reference values of the laboratory and your personal context.
Low vitamin D levels are common in the Netherlands, particularly in winter months. A low value provides insight into whether supplementation, through diet, sun exposure or supplements, may be worthwhile. Building up a good level is gradual: re-testing after a few months shows the effect.
A vitamin D level within the reference range gives a reassuring picture at this moment. Bear in mind that the level may drop in winter, periodic measurement can help identify a potential decline early.
An elevated vitamin D level is almost always seen with the use of high-dose supplements. Vitamin D is stored in adipose tissue; with prolonged high intake, the level can rise. Our doctor provides explanation and context for your result.
Hoe wij uw uitslag interpreteren
Our doctors interpret your vitamin D level based on the laboratory reference values and your personal context, such as age, season and possible supplement use. You receive a report in plain language, as a starting point for your own insight or a conversation with your healthcare provider.
Related tests
A single marker gives one perspective. For a broader picture you can combine Vitamin D with a theme package or related markers.
Veelgestelde vragen
No, fasting is not required for a vitamin D measurement.
With daily supplementation, a change is usually only visible in the blood after 8 to 12 weeks. Testing sooner therefore makes little sense.
25-OH vitamin D (25-hydroxy vitamin D) is the storage form in the blood and the standard measure of your vitamin D status. The active form (1,25-dihydroxy) is rarely measured and is not relevant for most questions.
In the period from February to April, levels are on average lowest, because the sun's strength in winter is insufficient to produce vitamin D in the skin.
Yes. A darker skin tone reduces the production of vitamin D under the influence of sunlight, compared to lighter skin, less vitamin D can be produced in the same amount of time.
No, the body regulates production via the skin. Excessive levels occur almost exclusively through prolonged use of high-dose supplements.
You receive a PDF report with your value and an explanation from our doctor. What you do with it, for example discussing it with your GP, adjusting supplements, or doing nothing, remains your own choice.
Yes, the report is written in medical language and contains all relevant laboratory information. Many clients bring it to their GP.
In the Health Guide
For €79 you receive your vitamin D level including personal explanation by a doctor, typically within 2 business days. No referral needed.
Order Vitamin D for €79 →Want to test multiple markers at once?
Combine Vitamin D with other markers via Bloodworks Select. Blood draw costs are waived from €225.
Customer service
Available on weekdays from 9:00 – 17:00
