Is ferric dextran (Intravenous Iron) a preferred method of IV iron for a patient with Hashimoto's (Autoimmune Thyroiditis)?

IV Iron Therapy in Patients with Hashimoto's Thyroiditis

Ferric carboxymaltose is the preferred IV iron formulation for patients with Hashimoto's thyroiditis due to its superior safety profile, efficacy, and convenience compared to iron dextran preparations.

Comparison of IV Iron Formulations for Hashimoto's Patients

Ferric Carboxymaltose (Preferred Option)

• Allows for complete iron repletion in 1-2 visits with higher single doses (750mg in US) 1
• Administration time of only 15 minutes 1
• No test dose required
• Lower risk of hypersensitivity reactions compared to iron dextran
• Cost-effective despite higher unit cost due to fewer required visits 1
• Most appropriate for patients with inflammatory conditions like autoimmune thyroiditis

Iron Dextran (Not Preferred)

• Carries a black box warning for anaphylaxis risk in the US 2
• Requires test dose administration 2
• Higher risk of hypersensitivity reactions due to larger carbohydrate shell 2
• Multiple visits may be required for complete iron repletion
• Delayed reactions characterized by arthralgias and myalgias are dose-related 2

Rationale for Avoiding Iron Dextran in Hashimoto's Patients

1. Autoimmune Risk: Patients with one autoimmune condition (Hashimoto's) have increased risk of hypersensitivity reactions to medications 3

2. Inflammatory State: Hashimoto's thyroiditis involves chronic inflammation, which can:

   • Impair oral iron absorption due to hepcidin upregulation 2
   • Increase risk of adverse reactions to IV iron preparations

3. Convenience Factor: Ferric carboxymaltose requires fewer visits for complete iron repletion compared to iron dextran 1

Administration Protocol for IV Iron in Hashimoto's Patients

Pre-administration Assessment

• Confirm iron deficiency (serum ferritin <30 ng/mL or <100 ng/mL with inflammation) 1
• Check for contraindications:
  • Hypersensitivity to any components
  • Evidence of iron overload
  • Active infection

Dosing Recommendations

For ferric carboxymaltose, follow this simplified dosing table 1:

Hemoglobin g/dL	Body weight <70 kg	Body weight ≥70 kg
10-12 (women)	1000 mg	1500 mg
10-13 (men)	1000 mg	1500 mg
7-10	1500 mg	2000 mg
<7	1500 mg + additional 500 mg	2000 mg + additional 500 mg

Monitoring

• Monitor patients for at least 30 minutes after infusion for hypersensitivity reactions 1
• Reassess iron status 8-12 weeks after completion of therapy 1
• Target parameters: hemoglobin ≥11-12 g/dL, ferritin >100 ng/mL, transferrin saturation >20% 1

Alternative IV Iron Options

If ferric carboxymaltose is unavailable, consider:

1. Ferric Derisomaltose (Monoferric)

   • Can administer up to 1500 mg in a single dose
   • 15-30+ minute administration time 1
   • No test dose required

2. Iron Sucrose (Venofer)

   • Maximum single dose of 200 mg
   • Multiple doses needed for complete repletion 1
   • No test dose required but recommended in patients with multiple drug allergies 2

3. Ferumoxytol (Feraheme)

   • 510 mg per dose
   • Multiple doses needed for complete repletion 1
   • No test dose required

Cautions and Contraindications

• Avoid IV iron during active infection 2
• Use caution in patients with multiple drug allergies
• Do not administer on the same day as anthracycline chemotherapy 1
• Monitor for hypophosphatemia, particularly with ferric carboxymaltose 4

By selecting ferric carboxymaltose over iron dextran for patients with Hashimoto's thyroiditis, clinicians can minimize the risk of adverse reactions while effectively treating iron deficiency with fewer healthcare visits.