Selenium Replenishment Management
Selenium replenishment should be initiated when plasma selenium falls below 0.4 mmol/L (<32 mg/L), starting with 100 mg/day via enteral or IV route, with the IV route preferred for rapid correction in severe deficiency, requiring up to 400 mg/day for 7-10 days. 1
Assessment and Monitoring
When to Measure Selenium Status
- Measure plasma selenium and CRP at baseline in all patients likely to receive parenteral nutrition for more than two weeks or commencing home parenteral nutrition 1
- Repeat measurements every 3-6 months during ongoing parenteral nutrition, or more frequently based on initial results 1
- Long-term enteral nutrition patients require monitoring as selenium deficiency may develop depending on the feeding product used 1
Interpreting Selenium Levels
Critical consideration: Inflammation significantly affects plasma selenium interpretation. 1
- CRP 10-40 mg/L: Expect 15-25% reduction in plasma selenium 1
- CRP 41-80 mg/L: Expect approximately 35% reduction 1
- CRP >80 mg/L: Expect approximately 50% reduction 1
Always measure CRP simultaneously with plasma selenium to correct for inflammatory redistribution, as selenium may return to normal without supplementation once inflammation resolves 1
Treatment Thresholds
Absolute Indications for Supplementation
- Plasma selenium <0.4 mmol/L (<32 mg/L): Always triggers supplementation regardless of inflammatory status 1
- Plasma selenium <0.75 mmol/L in patients without inflammation (CRP <20 mg/L): Initiate supplementation to prevent immune dysfunction and other non-specific consequences of depletion 1
Dosing Strategies
Standard Maintenance Requirements
- Home parenteral nutrition without inflammation: 60-100 mg/day to normalize plasma selenium 1
- Route selection: Enteral route preferred when gastrointestinal tract is available due to high absorption; IV route provides more rapid correction 1
Repletion Dosing for Deficiency
- Recent reduced intake with depletion: Up to 200 mg/day (twice normal daily amount) with monitoring of plasma selenium levels 1
- Oral administration acceptable if gastrointestinal tract is functional 1
- Prolonged enteral nutrition deficiency: 100 mg/day for 2 weeks should restore blood levels and reduce symptoms 1
High-Requirement Clinical Scenarios
Burns patients with high selenium losses:
- 375 mg/day IV provides more rapid healing and fewer infections 1
Major trauma and cardiac surgery patients:
- 275 mg/day may provide benefit 1
Renal replacement therapy patients:
- Increased amounts required due to increased losses and oxidative stress 1
Specific documented losses (e.g., continuous renal replacement therapy):
- Balance studies guide dosing, which may reach an additional 300 mg/day 1
Rapid Correction Protocol
For plasma selenium <0.4 mmol/L (30 mg/L):
- IV route for rapid correction: Up to 400 mg/day for at least 7-10 days 1
- Recheck status after initial correction period 1
Critical Pitfalls to Avoid
Do Not Use High-Dose Selenium in ICU
Meta-analysis shows no consistent benefit from massively increased selenium supply (1000-4000 mg/day) in ICU patients, and this practice is now advised against. 1 This represents an important shift from earlier speculation about potential benefits.
Monitor for Toxicity
- Upper toxicity limits: Plasma selenium 6-12 mmol/L before toxicity symptoms occur 1
- Chronic overexposure concerns: Positively associated with type 2 diabetes and high-grade prostate cancer 1
- Oral tolerable upper limit: 400 mcg/day 2
Account for Inflammation
Common error: Treating low selenium levels during acute inflammation without considering redistribution. Plasma selenium may normalize spontaneously as inflammation resolves without supplementation 1. Always interpret selenium levels in context of CRP values.