Selenium Dosing Recommendations
For healthy adults, the basic daily selenium requirement is 60-100 µg/day, while therapeutic dosing for deficiency ranges from 100-200 µg/day depending on severity, with higher doses (275-375 µg/day) reserved for specific high-loss conditions like burns or major trauma. 1
Standard Maintenance Dosing
The 2022 ESPEN micronutrient guidelines provide the most authoritative framework for selenium dosing:
- Baseline requirement for adults without inflammation: 60-100 µg/day 1
- Healthy adults (general population): 70 µg/day adequate intake 2
- Pregnant women: Same as non-pregnant adults (70 µg/day), as adaptive metabolic changes occur during pregnancy 2
- Lactating women: 85 µg/day (additional 15 µg/day to cover selenium secreted in breast milk) 2
Treatment of Selenium Deficiency
Dosing should be guided by plasma selenium levels and inflammation status (measured by CRP):
Mild to Moderate Deficiency
- Plasma selenium 0.4-0.75 µmol/L: Start 100 µg/day orally (enteral route preferred due to good absorption) 1
- Recent depletion from reduced intake: Up to 200 µg/day with monitoring 1
- Duration: 100 µg/day for 2 weeks should restore blood levels and reduce symptoms 1
Severe Deficiency
- Plasma selenium <0.4 µmol/L (<32 µg/L): This always triggers supplementation 1
- IV route for rapid correction: Up to 400 µg/day for at least 7-10 days, then recheck status 1
Special High-Dose Situations
Certain clinical conditions require substantially higher selenium doses due to increased losses or oxidative stress:
- Burns patients: 375 µg/day IV (associated with more rapid healing and fewer infections) 1
- Major trauma/cardiac surgery: 275 µg/day 1
- Renal replacement therapy: Increased amounts needed due to losses and oxidative stress 1
- Specific documented losses: May require up to 300 µg/day based on balance studies 1
Critical Considerations
Inflammation Correction Factor
Inflammation artificially lowers plasma selenium through redistribution, not true deficiency. You must measure CRP simultaneously and apply correction factors 1:
- CRP 10-40 mg/L: Expect 15-25% reduction in plasma selenium
- CRP 41-80 mg/L: Expect ~35% reduction
- CRP >80 mg/L: Expect ~50% reduction
Many patients normalize selenium without supplementation once inflammation resolves 1.
Route Selection
- Enteral route: Preferred when GI tract available due to high absorption 1
- IV route: Use for plasma selenium <0.4 µmol/L or when rapid correction needed 1
Pediatric Dosing
- Infants 7-11 months: 15 µg/day 2
- Children 1-3 years: 15 µg/day 2
- Adolescents 15-17 years: 70 µg/day 2
- Infants on parenteral nutrition: 6 µg/kg/day (reduction below this causes biochemical deficiency) 1
Safety Limits and Toxicity
Upper toxicity thresholds are not precisely defined but range from plasma selenium levels of 6-12 µmol/L 1. Important safety concerns:
- Avoid chronic high-dose supplementation: Selenium overexposure is positively associated with type 2 diabetes and high-grade prostate cancer 1
- ICU mega-dosing (1000-4000 µg/day) is NOT recommended: Meta-analysis shows no consistent benefit and is now advised against 1
- Long-term supplementation (100-300 µg/day for 5 years): Can alter thyroid function (decreased TSH and FT4) 1
Monitoring Strategy
For patients on parenteral nutrition >2 weeks or home PN: Measure plasma selenium and CRP at baseline 1. Recheck after 7-10 days of supplementation when treating deficiency.
Target plasma selenium concentration: ≥0.75 µmol/L in patients without inflammation to minimize consequences like impaired immune function 1.
Common Pitfalls
- Treating low selenium without checking CRP: May lead to unnecessary supplementation when inflammation is the cause
- Using excessive doses in ICU patients: No mortality/morbidity benefit demonstrated
- Ignoring route of administration: IV provides more rapid correction when severely deficient
- Overlooking high-loss states: Burns, trauma, and dialysis patients need substantially higher doses than standard recommendations