Selenium Blood Test

The Selenium blood test measures the concentration of selenium in the blood. Selenium is an essential trace mineral important for antioxidant defense, thyroid function, DNA synthesis, and immune health. Both selenium deficiency and toxicity can have significant health consequences.

1. What Is Selenium?

• Selenium is a trace element that supports several selenoproteins involved in antioxidant protection and metabolic processes.

• It plays a crucial role in the production of glutathione peroxidase, an enzyme that protects cells from oxidative damage.

• Selenium is also vital for proper thyroid hormone metabolism and immune response.

2. Why Is the Selenium Test Performed?

This test is used to:

• Evaluate selenium status in individuals with signs of deficiency or excess.

• Monitor nutritional levels in patients on long-term parenteral nutrition.

• Investigate unexplained fatigue, weakened immunity, or thyroid dysfunction.

• Monitor selenium supplementation in at-risk populations.

3. Selenium Reference Range

• Normal serum selenium levels: 70 – 150 µg/L (micrograms per liter)

• Optimal levels can vary slightly by laboratory and testing method.

4. Interpreting Selenium Test Results

🔹 Low Selenium:

• May result from inadequate dietary intake, malabsorption disorders, or long-term critical illness.

• Associated with impaired immune function, hypothyroidism, infertility, and increased oxidative stress.

🔹 High Selenium:

• May result from excessive supplementation or environmental exposure.

• Symptoms of toxicity include hair loss, brittle nails, garlic breath odor, fatigue, and in severe cases, neurological damage.

5. What Can Affect Selenium Levels?

• Dietary intake (foods like Brazil nuts, seafood, meats, and grains)

• Soil selenium content in different geographic regions

• Use of selenium supplements or multivitamins

• Gastrointestinal absorption issues (e.g., celiac or Crohn’s disease)

6. How Is the Test Performed?

• A blood sample is collected from a vein, typically using trace-element-free tubes.

• No fasting is required unless ordered alongside other tests.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Experience symptoms of selenium deficiency or toxicity.

• Have a condition affecting nutrient absorption.

• Are taking selenium supplements and want to monitor your levels.

🔹 Key Takeaways

✅ Selenium is essential for antioxidant activity, thyroid health, and immune defense.

✅ Both low and high levels can impact health; blood testing can ensure optimal balance.

✅ A balanced diet with selenium-rich foods typically provides adequate levels.