Is a serum selenium level of 192 safe?

Serum Selenium Level of 192 μg/L is Safe and Within Normal Range

A serum selenium level of 192 μg/L is safe and within the optimal range for health. According to clinical nutrition guidelines, plasma selenium concentrations of 1.5-1.9 μmol/L (approximately 118-150 μg/L) may be optimal for reducing mortality in free-living individuals 1.

Understanding Selenium Reference Ranges

Selenium levels can be measured in several ways:

• Plasma/serum selenium: The primary clinical measurement

  • Values <0.4 μmol/L (<32 μg/L) indicate definite deficiency requiring supplementation
  • Values <0.75 μmol/L in patients without inflammation should trigger supplementation
  • Optimal range: 1.5-1.9 μmol/L (118-150 μg/L) 1

• Upper safety limits:

  • Toxicity symptoms may begin to appear at plasma levels between 6-12 μmol/L (474-948 μg/L) 1
  • A level of 192 μg/L is well below this toxicity threshold

Interpreting Your Result

Your selenium level of 192 μg/L is:

1. Above the deficiency threshold of 0.75 μmol/L (59 μg/L)
2. Within the range considered beneficial for health
3. Well below toxicity levels that begin at approximately 474 μg/L

Factors Affecting Selenium Measurement

When interpreting selenium levels, consider these important factors:

• Inflammation: Inflammatory states can reduce plasma selenium levels by 15-50% depending on C-reactive protein (CRP) levels 1, 2
• Geographic variation: Reference intervals should ideally be locally established, as selenium content in soil and food varies by region 1
• Sample timing: Serum selenium can fluctuate by up to 20% during a 24-hour period 2

Clinical Significance of Adequate Selenium

Adequate selenium status is important for:

• Antioxidant function: Selenium is essential for glutathione peroxidase activity, which protects against oxidative damage 3
• Thyroid function: The thyroid contains the highest concentration of selenium per gram of tissue in the body 4, 3
• Immune system function: Selenium stimulates antibody formation and activity of helper T cells, cytotoxic T cells, and Natural Killer cells 5
• Potential cancer risk reduction: Some evidence suggests elevated selenium intake may be associated with reduced cancer risk, though this remains under investigation 6

When to Consider Supplementation

Selenium supplementation is generally not recommended for individuals with adequate levels:

• Supplementation is indicated when levels are <0.75 μmol/L (<59 μg/L) in the absence of inflammation 1, 2
• Special populations may require higher selenium intake:
  • Burns patients (up to 375 μg/day) 1
  • Major trauma patients (around 275 μg/day) 1
  • Patients on renal replacement therapy 1

Important Cautions

• Narrow therapeutic window: Selenium has a narrow margin between beneficial and potentially harmful effects 1
• Potential risks of excess: Selenium overexposure has been associated with type 2 diabetes and high-grade prostate cancer 1
• Not routinely recommended: Guidelines do not recommend routine selenium supplementation for most populations, including those with cystic fibrosis 1

Your selenium level of 192 μg/L indicates adequate status without the need for supplementation or concern about toxicity.