What is the recommended dose of immunoglobulin (Ig) for various medical conditions?

Immunoglobulin Dosing by Indication

The recommended dose of immunoglobulin varies significantly by indication, route of administration, and clinical context, with intramuscular preparations requiring weight-based dosing (0.02-0.6 mL/kg) for post-exposure prophylaxis and intravenous preparations requiring higher doses (100-2000 mg/kg) for immunodeficiency and autoimmune conditions. 1, 2

Intramuscular Immunoglobulin (IG) Dosing

Hepatitis A Prophylaxis

• Post-exposure prophylaxis: 0.02 mL/kg IM as a single dose, administered as soon as possible after exposure (effective only if given within 2 weeks) 3, 1
• Pre-exposure prophylaxis for travelers:
  • Short-term travel (2-3 months): 0.02 mL/kg IM as a single dose 3, 1
  • Prolonged travel (3-5 months): 0.06 mL/kg IM, repeated every 5 months 3, 1

Measles Prophylaxis

• Immunocompetent individuals: 0.25 mL/kg IM (maximum 15 mL), administered within 6 days of exposure 3, 1
• Immunocompromised individuals: 0.5 mL/kg IM (maximum 15 mL), administered within 6 days of exposure 3, 1

Critical caveat: IG should not be used to control measles outbreaks, only for individual post-exposure prophylaxis in susceptible contacts. 3

Tetanus Immune Globulin (TIG)

• Wound prophylaxis: 250 units IM for wounds other than clean, minor wounds in patients with unknown/uncertain vaccination status or fewer than three prior tetanus toxoid doses 3, 1
• Administer at a separate site from tetanus-diphtheria (Td) vaccine 3

Rabies Immune Globulin (HRIG)

• Post-exposure prophylaxis: 20 IU/kg body weight 3
• Infiltrate up to half the dose around the wound if anatomically feasible; administer the remainder IM 3
• Do not administer to previously vaccinated individuals with documented adequate rabies antibody titers 3

Vaccinia Immune Globulin (VIG)

• Treatment dose: 0.6 mL/kg IM for eczema vaccinatum, vaccinia necrosum, or ocular vaccinia 3, 1
• Divide doses over 24-36 hours due to large volume (e.g., 42 mL for a 70-kg person) 3, 1
• May repeat every 2-3 days until no new lesions appear 3
• Not effective for post-vaccination encephalitis 3

Intravenous Immunoglobulin (IVIG) Dosing

Primary Immunodeficiency/Antibody Deficiencies

• Standard replacement therapy: 300-400 mg/kg IV every 3-4 weeks 1, 2, 4, 5
• Initial dose: 300-400 mg/kg IV monthly, may increase frequency to every 2-3 weeks if needed 5, 6
• Target IgG trough levels: >5 g/L for agammaglobulinemia, ≥3 g/L above baseline for common variable immunodeficiency (CVID) 5, 7

Evidence note: The 400 mg/kg dose is superior to 200 mg/kg in preventing lower respiratory tract and severe infections, raising trough IgG from 4.3 to 6.5 g/L. 7

Idiopathic Thrombocytopenic Purpura (ITP)

• Standard dose: 400 mg/kg IV daily for 2-5 consecutive days 1, 4, 6
• Alternative regimen: 1 g/kg IV as a single dose, may repeat if necessary 2
• Maintenance therapy with repeat 400 mg/kg doses has been used 6

Kawasaki Disease

• Standard dose: 2 g/kg IV as a single infusion 1, 2

Autoimmune/Inflammatory Conditions

• Idiopathic inflammatory myopathies: 1-2 g/kg of ideal body weight over 2 consecutive days 2
• Guillain-Barré syndrome: 0.4 g/kg/day for 5 days (total 2 g/kg) 2
• Multisystem inflammatory syndrome in children (MIS-C): 2 g/kg based on ideal body weight 2
• Immune-related adverse events from checkpoint inhibitors: 2 g/kg over 5 days 2

Invasive Bacterial Infections with Hypogammaglobulinemia

• Prophylactic dose: 400 mg/kg IV every 2-4 weeks 2

Critical Administration Considerations

Route-Specific Safety

• Never administer intramuscular IG intravenously - only IVIG preparations modified for IV use can be given intravenously 3, 1
• Never dilute intramuscular IG - it is provided ready for use 1
• IVIG must be reconstituted only with manufacturer-provided diluent, never saline 1

Pre-Administration Assessment

• Screen for IgA deficiency before IVIG to prevent anaphylaxis; use IgA-depleted preparations if deficiency detected 1, 2, 6
• Absolute contraindications include IgA deficiency with detectable IgA antibodies, acute allergic reaction to thimerosal (for VIG), and history of severe reaction to human immunoglobulin 1, 6

Special Populations

• Obese patients (BMI ≥30 kg/m²): Use ideal body weight or adjusted body weight rather than actual body weight for IVIG dosing 2
• Cardiac dysfunction: Consider divided dosing (1 g/kg daily over 2 days) to minimize fluid overload 2
• Pregnancy and lactation: Not contraindications for immunoglobulin administration 1

Vaccine Interactions

• IG interferes with live attenuated vaccines 1
• Delay MMR vaccination >3 months after IG for hepatitis A, and 5-6 months after IG for measles 1

Monitoring

• Monitor renal function (urine output, serum creatinine) during IVIG administration 2
• Consider premedication with diphenhydramine and acetaminophen; corticosteroids for patients with prior infusion reactions 2