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Selenium test: when to take it and why this trace element is so important
What is selenium and why should you check it?
Selenium is a vital trace element involved in thyroid function, cellular protection from oxidative stress, immune function, and reproductive health. Its deficiency or excess can seriously affect metabolism, energy balance, antioxidant defense, and even mood.
A selenium analysis allows you to determine the concentration of this element in the body and identify disorders that often occur without obvious symptoms.
When should you get tested for selenium?
At chronic fatigue, decreased immunity, frequent colds
In case decreased thyroid function (hypothyroidism, autoimmune thyroiditis)
If there is problems with skin, hair, nails
In patients with infertility or decreased libido
After long-term intake of antioxidants, vitamins, dietary supplements
At suspected intoxication or selenium overdose
How to prepare for the analysis
Blood donation in the morning on an empty stomach
8–12 hours before blood sampling — do not eat, drink coffee or tea
Preferably within 3–5 days do not take vitamin complexes containing selenium
In consultation with the doctor - stop taking dietary supplements
The analysis is performed on venous blood, less often on urine or hair (to assess chronic levels).
What level of selenium is considered normal?
In most laboratories, normal values for blood are:
70–130 μg/l — overall normal range
< 70 μg/l — selenium deficiency
130 mcg/l — level up (possible intoxication)
Optimal values may depend on age, gender, and physiological condition (pregnancy, thyroid disease).
Table: What the analysis result means
| Selenium level | What does this mean | Possible causes |
|---|---|---|
| < 70 μg/l | Deficit | Unbalanced diet, digestive diseases |
| 70–130 μg/l | Norm | Physiologically optimal level |
| > 130 μg/l | Excess | Excessive use of dietary supplements, intoxication, selenosis |
How to replenish selenium deficiency
Foods rich in selenium: Brazil nuts, fish, eggs, seafood, liver
In case of significant deficiency, a doctor may prescribe selenium preparations (selemethionine, sodium selenite)
Importantly: do not self-medicate, because selenium is toxic in high doses
References to sources
Mayo Clinic – Selenium: Why you need it
FDA - Selenium information for consumers
A selenium test is a simple test that helps assess this important component of health. It is recommended not only for diseases, but also for the prevention of deficiencies, which often go unnoticed.
