What initial investigations are required for patients starting dimethyl fumarate (Tecfidera)?

Initial Investigations Required for Starting Dimethyl Fumarate

Before starting dimethyl fumarate (Tecfidera), a complete blood count with lymphocyte count, liver function tests, and renal function tests are essential baseline investigations to ensure patient safety and monitor for potential adverse effects. 1

Required Baseline Laboratory Tests

• Complete blood count (CBC) with differential, including lymphocyte count - critical due to risk of lymphopenia 1
• Liver function tests (LFTs) - to monitor for potential hepatotoxicity 1
• Serum chemistry profile including renal function tests (creatinine, BUN) 1
• Urinalysis - to establish baseline renal function 2

Monitoring Schedule After Initiation

• CBC with lymphocyte count:

  • At 6 months after starting treatment 1
  • Then every 6-12 months thereafter 1
  • More frequent monitoring may be needed if lymphopenia develops 1

• Liver function tests:

  • Monitor as clinically indicated 1
  • Consider discontinuation if clinically significant liver injury is suspected 1

• Serum chemistry and urinalysis:

  • Every 2 weeks for the first month 2
  • Monthly for the first 6 months 2
  • Bimonthly thereafter 2

Special Considerations and Precautions

Lymphopenia Risk Management

• Dimethyl fumarate may decrease lymphocyte counts by approximately 30% during the first year 1
• Consider interruption of treatment if lymphocyte counts remain below 0.5 x 10^9/L for more than 6 months 1
• Be aware that severe, persistent lymphopenia can occur and may not resolve quickly after discontinuation 3

Liver Injury Monitoring

• Cases of clinically significant liver injury have been reported with dimethyl fumarate 1
• Discontinue treatment if clinically significant liver injury is suspected 1
• Signs of liver injury include elevation of aminotransferases >5x upper limit of normal and bilirubin >2x upper limit of normal 1

Other Potential Adverse Effects to Monitor

• Gastrointestinal effects (abdominal cramps, nausea, diarrhea) 2
• Flushing (occurs in approximately 40% of patients) 1
• Potential opportunistic infections, including herpes zoster 1

Clinical Pitfalls to Avoid

• Failure to monitor lymphocyte counts: Prolonged severe lymphopenia can lead to opportunistic infections including PML 1, 3
• Delayed recognition of liver injury: Regular monitoring of LFTs is essential to detect early signs of hepatotoxicity 1
• Inadequate patient education: Patients should be informed about potential side effects and the importance of adherence to monitoring schedules 4
• Missing early signs of serious infections: Consider withholding treatment in patients with serious infections until resolution 1

By following these monitoring guidelines, clinicians can help ensure the safe use of dimethyl fumarate while minimizing the risk of serious adverse events.