A blood test result indicating a selenium level outside the normal range can raise questions. Understanding the meaning of this number is an important step to correctly interpret your health report. This article provides factual insight into selenium, an essential trace element, to help you better understand your results.

Selenium (symbol Se) is a mineral our body needs in small quantities to function optimally. The body does not produce it itself. It must therefore obtain it through food. Once absorbed by the intestine, selenium is transported in the blood, where it integrates into specific proteins called selenoproteins.

These proteins have crucial roles. The best known, glutathione peroxidase, is a powerful antioxidant that protects cells against damage caused by free radicals. Selenium also contributes to the proper functioning of the immune system and the thyroid gland. Blood testing assesses nutritional status and investigates certain symptoms.

The Importance of Monitoring Your Selenium Levels

Selenium interacts with many biological processes. A imbalance, whether a deficiency or an excess, can therefore have repercussions on health.

Scientific research has progressively revealed the essential nature of this mineral. An undetected anomaly may be associated with long-term risks. For example, studies suggest that chronic selenium deficiency can be a risk factor for certain cardiovascular diseases and may be linked to cognitive decline in older adults.

Selenium concentration in soils varies greatly between regions of the world. This directly influences the content of food and can lead to suboptimal intakes in some populations. For a doctor, selenium levels are therefore a useful biomarker for investigating thyroid disorders, monitoring patients with intestinal diseases, or assessing unexplained chronic fatigue.

How to Read Your Selenium Test Results?

On your blood report, selenium is often expressed in micrograms per liter (µg/L). The presentation includes your result as well as the laboratory’s reference values.

Understanding Reference Values

An example result could be:

• Serum Selenium: 86 µg/L
• Reference Values: 70-120 µg/L

Reference values may vary slightly from one laboratory to another. Analysis methods and local population characteristics explain this difference. You should therefore always compare your result to the norms indicated in your report. Generally, a color or symbol (arrow, asterisk) highlights out-of-range values.

Quick Interpretation Checklist

• Identify your value and the laboratory’s reference range.
• Note the deviation between your result and the normal limits.
• Check if other parameters are also abnormal (e.g., thyroid function).
• Consult your previous results to see an evolution.
• Consider your recent diet and supplements.

Diseases Linked to Selenium Level Imbalance

An abnormal selenium level can be a sign of various medical conditions.

Diseases Linked to Selenium Deficiency

A prolonged and severe selenium deficiency is rare in developed countries, but scientists can associate it with specific diseases.

Keshan Disease Cardiomyopathy

Researchers identified this heart disease in regions of China where soils are extremely poor in selenium. The lack of this trace element makes the heart muscle more vulnerable to oxidative damage and certain viral infections, which can lead to heart failure.

Kashin-Beck Disease

This is a bone and joint disease (osteoarthropathy) also observed in selenium-deficient regions. The deficiency alters cartilage development and protection, leading to joint deformities and chronic pain.

Thyroid Dysfunction

Selenium is essential for the conversion of thyroid hormone T4 into its active form T3. A deficiency can therefore disrupt this function and lead to symptoms of hypothyroidism such as fatigue, weight gain, or cold sensitivity.

Decreased Immunity

Selenium contributes to a good immune system response. A lack can weaken the body’s defenses, which can result in more frequent infections or slower healing.

Diseases Linked to Selenium Excess (Selenosis)

An excess of selenium, called selenosis, is almost always due to excessive supplementation or environmental exposure in very rare regions of the world. Symptoms can include garlic-smelling breath, hair loss, brittle nails, digestive problems, and fatigue. In the most severe cases, liver toxicity may occur.

Practical Tips for Managing Your Selenium Levels

Depending on your result, and always in agreement with your doctor, here are some courses of action.

Adjust Your Diet

• To increase a low level: The most concentrated source is Brazil nuts. One or two per day are usually sufficient to meet the needs. Other good sources include fish and seafood, organ meats, meats, and eggs.
• To reduce a high level: The first step is to stop any supplementation containing selenium. It is then advisable to limit the consumption of the richest foods, especially Brazil nuts.

Follow-up and Medical Consultation

The follow-up frequency depends on the situation. A slight abnormality can be monitored after 3 months of dietary adjustment. A more marked deficiency or excess requires a medical consultation for closer monitoring and investigation of possible causes.

A consultation is strongly recommended if the level is very abnormal (<50 µg/L or >150 µg/L) or if it is accompanied by persistent symptoms.

Frequently Asked Questions About Selenium

Do I Need a Selenium Test?

This dosage is not a routine examination. A doctor prescribes it in case of suggestive symptoms, chronic digestive disorders, artificial nutrition monitoring, or certain thyroid problems.

Is Selenium Testing Reimbursed?

In France, reimbursement by health insurance is subject to specific medical indications (e.g., parenteral nutrition monitoring, suspected deficiency in a pathological context). Outside of these cases, the analysis may be at the patient’s expense.

Do I Need to Fast for the Test?

Fasting is not strictly mandatory. However, most laboratories recommend it to standardize collection conditions.

Are there Interactions with Medications?

Yes. Selenium can interact with certain anticoagulants, statins, or chemotherapy treatments. It is essential to inform your doctor of any supplementation if you are on medication.

What is the Difference Between Forms of Selenium in Supplements?

Selenium supplements contain organic forms (selenomethionine), which the body absorbs and stores better, and inorganic forms (selenite). For this reason, health professionals and nutrition experts often prefer organic forms for long-term supplementation.

Additional resources

• To deepen your knowledge of this blood marker, click here.
• To extend your knowledge and decipher other markers, more articles are available here.

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