Selenium is an essential element. It is a cofactor required to maintain activity of glutathione peroxidase (GSH-Px), an enzyme that catalyzes the degradation of organic hydroperoxides. The absence of selenium correlates with loss of GSH-Px activity and is associated with damage to cell membranes due to accumulation of free radicals.

Whole blood selenium levels are within the normal reference range. This measurement reflects long-term selenium status, while urinary selenium levels are better indicators of recent intake.

Selenium is an essential trace element with critical roles in:

• Thyroid hormone metabolism

• Antioxidant defense (especially via glutathione peroxidase)

• Maintaining cellular redox balance

Low selenium levels are linked to thyroid dysfunction, particularly Hashimoto’s thyroiditis, and reduced conversion of thyroxine (T4) to triiodothyronine (T3).

Selenium, a trace element essential for human health, plays a critical role in various physiological processes and is commonly assessed through its concentration in serum. As an integral component of selenoproteins, selenium is pivotal in antioxidant defense systems, thyroid hormone metabolism, and immune function. The primary dietary sources of selenium include nuts, cereals, meat, fish, and eggs, with its bioavailability influenced by soil composition and dietary factors. Serum selenium levels are reflective of both short-term and long-term selenium status, offering a reliable biomarker for nutritional assessment. The typical reference range for serum selenium varies, but is generally considered to be between 70 and 150 ng/mL.

Selenium is normally found in hair at very low levels, and several studies provide evidence that low hair Selenium is reflective of dietary intake and associated with cardiovascular disorders. Utilization of hair Selenium levels to assess nutritional status, however, is complicated by the fact that use of Selenium- or sulfur-containing shampoo markedly increases hair Selenium (externally) and can give a false high value.

Sources:

The selenium content of grains and vegetables depends on the selenium content of the soil. In meats, selenium content is dependent on the diet of the animals. Foods with higher selenium content include Brazil nuts, seafood (especially tuna), chicken, beef, pork, lamb. Also present in air, water, soil, metallurgy, airborne coal/oil emissions, dandruff shampoo, paints, photo cells, drums, photocopiers, glass, ceramics, rubber, pharmaceuticals.

Absorption factors:

Selenium tends to be well absorbed, and the bioavailability of selenium in the form of selenomethionine is greater than 90%. Sulfur, lead, arsenic, calcium and iron reduced the absorption of selenium. Urine is the main route of excretion and reflects recent dietary intake. Plasma is useful for assessing nutritional selenium status.

The trace mineral selenium functions primarily as a component of the antioxidant enzyme, glutathione peroxidase. Glutathione peroxidase activity, which requires selenium for activity, facilitates the recycling of vitamins C and E, in optimizing the performance of the antioxidant system.

Selenium is an essential element. It is a cofactor required to maintain activity of glutathione peroxidase (GSH-Px), an enzyme that catalyzes the degradation of organic hydroperoxides. The absence of selenium correlates with loss of GSH-Px activity and is associated with damage to cell membranes due to accumulation of free radicals.

Selenium is normally found in hair at very low levels, and several studies provide evidence that low hair Selenium is reflective of dietary intake and associated with cardiovascular disorders. Utilization of hair Selenium levels to assess nutritional status, however, is complicated by the fact that use of Selenium- or sulfur-containing shampoo markedly increases hair Selenium (externally) and can give a false high value.

Selenium is a mineral found in soil, water, and some foods. We need trace amounts for normal health, and selenium is an essential element in several metabolic pathways. It also has antioxidant properties that help prevent cellular damage from free radicals.

Selenium is required for thyroid function. Selenium is an essential component of the enzymes that convert Thyroxine (T4) to Triodothyronine (T3). Selenium is also important in heavy metal detoxification and is also important in enhancing immune system function.

Selenium (Se) is normally found in hair at very low levels, and several studies provide evidence that low hair Se is reflective of dietary intake and associated with cardiovascular disorders. Utilization of hair Se levels to assess nutritional status, however, is complicated by the fact that use of Se- or sulfur-containing shampoo markedly increases hair Se (externally) and can give a false high value.

Selenium is an essential element. It is a cofactor required to maintain activity of glutathione peroxidase (GSH-Px), an enzyme that catalyzes the degradation of organic hydroperoxides. The absence of selenium correlates with loss of GSH-Px activity and is associated with damage to cell membranes due to accumulation of free radicals.

Selenium, RBC – What Does It Mean?

Selenium, RBC (Red Blood Cells) measures intracellular selenium levels, providing a better reflection of long-term selenium status compared to a standard serum selenium test. Selenium is a trace mineral essential for antioxidant defense, thyroid function, immune health, and detoxification.

Why Is This Test Important?

Selenium is crucial for:
- Antioxidant protection – A key component of glutathione peroxidase, which neutralizes harmful free radicals.
- Thyroid hormone production – Necessary for converting T4 (thyroxine) into T3 (triiodothyronine), the active thyroid hormone.
- Immune function – Supports immune cell activity and reduces inflammation.
- Heavy metal detoxification – Helps eliminate toxic metals like mercury.
- Cognitive and cardiovascular health – Supports brain function and prevents oxidative stress in the heart.

RBC selenium levels provide a longer-term view (about 3–4 months) of selenium status, unlike serum selenium, which can fluctuate with recent dietary intake.