Insight into your selenium level.
Selenium is a trace element with a role in the thyroid, immune defence and the protection of cells against damage. A measurement gives insight into the amount of selenium in your blood.
Also known as: Se
Personal assessment by our BIG-registered doctors
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Background
What is selenium?
Selenium is an essential trace element. Essential means your body cannot make it and you obtain it through food. Trace element means you need only very small amounts. The body incorporates selenium into a small group of proteins, the selenoproteins. These are involved in neutralising harmful substances inside the cell, in converting thyroid hormone into its active form, and in the functioning of the immune system.
The measurement we perform is serum selenium, the selenium in the fluid part of your blood. That value mainly follows your intake over the past few weeks. It is therefore a snapshot and not a reflection of the stores in your tissues. As with zinc, ongoing inflammation can temporarily lower serum selenium, even without a deficiency. The result is therefore best interpreted in context, for example alongside an inflammation marker.
In brief
Trace element
Essential, obtained through food
Thyroid
Needed to convert thyroid hormone into its active form
Narrow margin
Too little and too much are closer together than for most nutrients
Dutch soil
Low in selenium; intake comes mainly from grains, meat, fish and eggs
Common reasons to test
When can insight into your Selenium be valuable?
Below are some situations in which measuring Selenium can provide insight.
Insight into your status
A test gives a snapshot of your serum selenium.
Before you start supplementing
With selenium, too little and too much lie closer together than for most nutrients. Measuring before you begin shows whether topping up makes sense at all.
If you already take supplements
If you use a selenium supplement, possibly alongside Brazil nuts, a measurement shows where you end up.
If you have questions about your thyroid
Selenium is needed to convert thyroid hormone into its active form. With a known thyroid condition the level can form part of a broader picture.
On a strongly restricted diet
If you eat no meat, fish or eggs, or follow a strict diet, your intake comes mainly from grains. A measurement then gives you something to go on.
With reduced absorption
In bowel disorders, after bariatric surgery or during long-term tube feeding, the body absorbs nutrients less well.
With unexplained hair or nail complaints
Both a deficiency and an excess of selenium are associated with brittle nails and hair loss. A measurement makes clear which way it points.
What your result means
How do we read your Selenium level?
Selenium is measured in micromoles per litre (µmol/L). The laboratory supplies the reference values. Serum selenium mainly follows intake over the past few weeks and can fall during inflammation, so the result is best interpreted alongside the rest of the picture.
A low value
A low serum selenium fits with limited intake or reduced absorption, for example in bowel disorders, after bariatric surgery or on a strongly plant-based diet. Ongoing inflammation can also temporarily lower the value without a deficiency being present. Severe deficiency is rare in the Netherlands. Our doctor looks at the whole picture rather than this number alone.
A normal value
A serum selenium within the laboratory's reference values is a reassuring result for this marker. Bear in mind that blood mainly reflects your intake over recent weeks and not the stores in your tissues. A single measurement is not a diagnosis.
An elevated value
An elevated serum selenium is usually caused by supplements, sometimes combined with a generous amount of Brazil nuts. With selenium, the margin between enough and too much is small. Prolonged excess can cause brittle nails, hair loss, gastrointestinal complaints and a garlic-like breath. Our doctor will discuss what the result means for you and whether an adjustment is sensible.
How we interpret your result
Related tests
Often combined with Selenium.
A single marker gives one perspective. For a broader picture you can combine Selenium with a theme package or related markers.
+ €29 blood draw fee per orderFree from €225
Frequently asked questions
Everything you want to know
Do I need to fast for a selenium test?
Fasting is not necessary for selenium. A blood draw in the morning gives the most comparable result. If you combine the test with glucose or cholesterol, for example, the fasting instructions do apply to those tests.
Can I get too much selenium?
Yes. With selenium the recommended amount and the upper limit lie closer together than for most nutrients. A prolonged excess can cause brittle nails, hair loss, gastrointestinal complaints and a garlic-like breath. That is exactly why it is worth measuring before you start supplementing, and certainly if you already do.
How many Brazil nuts can I eat?
Brazil nuts are by far the richest source of selenium, but the amount per nut varies widely and depends on where the tree grew. A few nuts a day already provide well over the daily requirement. If you eat them daily and also take a supplement, measuring is sensible.
Is selenium part of thyroid testing?
Selenium is needed to convert thyroid hormone into its active form, and the thyroid contains relatively high amounts of selenium. With a known thyroid condition the level can therefore add useful information. For the working of the thyroid itself you look at TSH and free T4.
Why do you measure serum and not whole blood?
Serum selenium is the measurement laboratories in the Netherlands perform as standard, and it follows your intake over the past few weeks. Whole blood or red blood cells reflect a longer period, but that test is not available everywhere. The doctor takes into account that serum is a snapshot.
How quickly does my level change if I start supplementing?
Serum selenium responds to a change in intake within a few weeks. If you want to see the effect of a supplement or an adjusted diet, measuring again after about three months is common.
Is selenium deficiency common in the Netherlands?
Severe deficiency is rare here. Dutch soil is low in selenium, so intake comes mainly from grains, meat, fish and eggs. Anyone who largely leaves those out, or who absorbs nutrients less well, sits lower. A measurement settles that question.
What happens if my level is abnormal?
You receive your result with a personal explanation from our doctor, who explains what the value means in your situation and whether further testing or an adjustment is worthwhile. If you have symptoms, your GP remains the right starting point, because an assessment involves more than blood alone.
Ready for insight into your selenium level?
You receive your selenium level including a personal explanation from a doctor, usually within 2 working days. No referral needed.
Order Selenium →Want to test multiple markers at once?
Combine Selenium with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from €225.
65,-
+ €29 blood draw fee+ €29 blood draw fee per order