Vitamin D3 Deficiency? 25-OH vitamin D level
This blood test measures the level of 25-hydroxyvitamin D [25(OH)D] in the blood. This is the most important marker for assessing the body’s vitamin D status.
What is vitamin D?
Vitamin D is a fat-soluble vitamin that plays an important role in the absorption of calcium and phosphorus and, therefore, in maintaining strong bones and teeth. In addition, vitamin D is involved in the normal functioning of the muscles and the immune system.
The body can produce vitamin D on its own in the skin when exposed to sunlight. We also get vitamin D from food, particularly from fatty fish, eggs, and foods fortified with vitamin D. If production and intake are insufficient, a deficiency can develop.
What does this test measure?
This test measures 25-hydroxyvitamin D [25(OH)D] in the blood. This is the most important circulating form of vitamin D and the standard blood marker used to assess the body’s vitamin D status.
25-OH vitamin D should not be confused with 1,25-dihydroxyvitamin D [1,25-(OH)â‚‚D], the biologically active form of vitamin D. This active form is primarily produced in the kidneys, and its concentration is influenced by factors such as calcium, phosphate, and parathyroid hormone (PTH).
Measuring 1,25-(OH)â‚‚-vitamin D is therefore primarily used for specific medical purposes and not as a standard test to assess vitamin D status.
When might it be a good idea to get tested for vitamin D?
Testing for 25-OH vitamin D may be useful when there is a medical reason to suspect low or abnormal vitamin D levels, for example in cases of:
conditions that may reduce the absorption of nutrients in the intestine;
certain bone or calcium metabolism disorders;
use of medications that may affect vitamin D metabolism;
a previously diagnosed vitamin D deficiency where medical monitoring is recommended;
long-term use of higher doses of vitamin D when monitoring by a doctor or healthcare provider is recommended;
Other medical conditions in which vitamin D status may be relevant.
Factors such as limited exposure to sunlight, a darker skin tone, or keeping most of the skin covered can increase the risk of low vitamin D levels.
A low vitamin D level
A low 25-OH vitamin D level indicates low vitamin D status. The significance of the result depends on the measured value, the reference ranges used, and the individual’s medical situation.
Possible factors that may contribute to low levels include:
limited exposure to sunlight;
insufficient vitamin D intake;
reduced absorption in the intestines;
certain liver or kidney conditions;
Use of medications that affect vitamin D metabolism.
The results should ideally be interpreted in conjunction with the patient’s age, symptoms, any existing medical conditions, and other relevant laboratory values.
Elevated vitamin D levels
Elevated 25-OH vitamin D levels are usually caused by excessive vitamin D intake from supplements. Vitamin D toxicity does not normally result from exposure to sunlight alone.
Very high levels of 25-OH vitamin D can lead to elevated calcium levels in the blood (hypercalcemia). This can cause symptoms such as nausea, fatigue, excessive thirst, and frequent urination, and in cases of severe or prolonged elevations, it can be harmful to the kidneys, among other organs.
Vitamin D toxicity is rare and is almost always caused by long-term intake of excessive doses of vitamin D supplements.
What can you do if your vitamin D levels are low?
The appropriate course of action depends on the measured level, age, diet, exposure to sunlight, and any medical conditions or medications.
Vitamin D can be obtained from sunlight, food, and supplements. If your levels are significantly low, you’re experiencing symptoms, have a medical condition, or are unsure about the appropriate dosage, it’s wise to discuss the results with a doctor or other healthcare provider.
A follow-up test isn’t necessary for everyone. If you’re being treated for a confirmed deficiency or are taking higher doses over a long period of time, your doctor or healthcare provider may recommend retesting your levels.
See also:Is your vitamin D level high enough?
PGO-info
Preventive blood test · Category 2 PGO
Legally required PGO information. Please read this and check the box to indicate your agreement before placing your order.
1. What is the purpose of this test?
This test measures your vitamin D level (25-OH) in the blood. The test is used to detect a vitamin D deficiency or excess, which may be associated with bone problems, muscle complaints, or low mood.
The test does not replace a doctor and does not diagnose.
2. Is this test something for you?
This test is suitable for adults (18+) who:
Want to have your vitamin D levels checked as a preventive measure?
Do you have symptoms that could be related to a deficiency, such as bone pain or muscle weakness?
Not getting much sun, for example, due to night shifts, dark skin, or covering your skin completely
Want to monitor their vitamin D intake or supplementation?
Are you pregnant or being treated for a serious medical condition? Please call us first. Our medical team will help you determine whether this test is appropriate for you.
3. How reliable is it?
The test is performed in an ISO-certified laboratory. Your vitamin D level is a snapshot in time and is influenced by factors such as the season, the amount of sunlight you’ve recently been exposed to, and certain medications. If the result is abnormal, it is sometimes advisable to repeat the test after some time has passed.
The reference ranges are based on your gender and age. Are you ordering under a different name? If so, make sure your date of birth is correct; otherwise, the reference ranges will be inaccurate.
4. How does the blood draw work?
Your blood will be drawn from a vein in your arm (venous blood draw) at one of the 1,000+ blood draw locations throughout the Netherlands. The blood draw is performed by a BIG-registered healthcare professional, or by someone who has been granted extended authority by a BIG-registered physician, who has determined that the healthcare professional is qualified and competent to perform this procedure.
The risks associated with blood collection are minimal:
Sometimes a bruise or some pain at the puncture site, but this goes away quickly
Rarely, a feeling of lightheadedness or dizziness; this goes away on its own
Minimal risk of infection thanks to sterile materials and hygienic procedures.
Do you use blood thinners? Report that in advance at the lancing station.
5. What happens if something deviates?
If your results are abnormal, we’ll guide you through the process:
Do the results require immediate medical follow-up? If so, we’ll call you personally before you see the results online.
Other abnormal values are indicated by an up or down arrow in your results.
You can discuss your results with your own primary care physician, who can assess whether further action is needed and, if so, what the appropriate next step is for you. In addition, through our Extra Services, you can request a consultation with one of our doctors, internists, or coaches.
We do not diagnose or give treatment advice. We do help you find the right way.
6. And if something unexpected comes out?
A vitamin D test is a targeted test, but even here, a result can sometimes call for extra attention that you didn’t expect—for example, if a value falls significantly outside the expected range. We call this an incidental finding. We always inform you of this in your results. Our medical team can help you determine whether further steps are necessary.
7. Can this be relevant to my family?
A vitamin D deficiency is usually related to lifestyle and exposure to sunlight, and generally has no direct genetic component. If your results do raise questions about your family’s health, please discuss this with your primary care physician.
8. What do we do with your data?
Your data is safe with us:
We never share your results with insurance companies or doctors (including primary care physicians).
The blood tubes are labeled with a unique barcode that only the laboratory can link to your test; no one else can determine what is being tested
Your results will be sent exclusively to the email address you provided.
We store your medical records for 20 years in a secure file on mijnuitslag.nl, as required by law
Only authorized staff have access, and we do not share any information with third parties without your consent
You can always view your data or have it deleted at [email protected].
More information: www.bloodtesting.nl/service/privacy-policy/
9. Good to know
This is a preventive test, not a medical treatment. The results do not constitute a diagnosis and are not a substitute for a doctor’s advice.
Have questions about your results or health? Contact our medical team.
This test meets the Quality Standard Preventive Health Examination (NVvPG) and is performed in accordance with the BIG Act and WGBO.
