IVIG Dose Calculator
Enter the patient weight, height, sex, prescribed dose in g/kg, and IVIG product concentration to get the total dose in grams, the volume to infuse, the dosing weight used (ideal or adjusted body weight for obese patients), and a titrated infusion schedule. Switch between metric and imperial. All calculations mirror current pharmacy and clinical-pharmacology consensus for IVIG dosing in adults.
Formula
Worked example
A 100 kg male, 175 cm tall (BMI 32.7, obese). IBW = 50 + 2.3 x (68.9 - 60) = 70.4 kg. AdjBW = 70.4 + 0.4 x (100 - 70.4) = 82.2 kg. Prescribed 2 g/kg for CIDP over 2 days: total dose = 82.2 x 2 = 164.4 g. Daily dose = 82.2 g. At 10% concentration: 822 mL per day. Standard titration: 30 mL/hr for 30 min, 60 mL/hr for 30 min, 90 mL/hr ... ramping to 300 mL/hr, total around 3.5 hours per day.
How IVIG dosing works
Intravenous immunoglobulin (IVIG) is a pooled human plasma product given to treat a wide range of immune deficiencies and autoimmune conditions. Doses are expressed as grams per kilogram (g/kg) of body weight, but for patients with a BMI at or above 30, using actual body weight would lead to substantially higher doses than needed for the intended pharmacological effect. Clinical pharmacologists and pharmacy guidelines therefore recommend using ideal body weight (IBW) as the dosing anchor, or an adjusted body weight (AdjBW = IBW + 0.4 x excess weight) for obese patients. This calculator applies the Devine formula to derive IBW, then checks BMI to decide which weight to use.
Understanding the infusion titration schedule
IVIG must be infused slowly and titrated upward to reduce the risk of acute reactions such as flushing, headache, back pain, and, more rarely, anaphylaxis or thromboembolic events. The standard protocol starts at 30 mL/hr for the first 30 minutes, then increases in 30 mL/hr increments every 30 minutes up to a typical ceiling of 200-300 mL/hr, depending on the product and patient tolerance. Patients who have tolerated multiple IVIG courses without reactions may be eligible for a rapid protocol starting at 60 mL/hr. The titration table generated by this calculator shows rate, step duration, and volume for each step, so nursing staff can follow a clear escalation plan.
Why body weight selection matters
Studies comparing IBW-based and ABW-based dosing in overweight IVIG recipients show similar clinical efficacy with measurable cost savings when IBW or AdjBW is used for obese patients. The Ontario provincial immunoglobulin utilization program mandates adjusted weight for BMI above 30. Using the patient's actual body weight when it falls below IBW (for example in underweight or paediatric patients) avoids under-dosing. This calculator automatically selects the appropriate weight and shows exactly which weight was used and why, supporting transparent clinical documentation.
Indication-based dose presets
Typical doses range from 0.4 g/kg per month for primary immunodeficiency replacement therapy to 2.0 g/kg for inflammatory conditions such as CIDP, Guillain-Barre syndrome, and Kawasaki disease. The presets in this calculator follow widely cited references and guidelines, but they are a convenience, not a prescription. The prescriber must confirm the dose, which may differ based on the patient's clinical response, renal function, prior reactions, and local institutional protocol. Note that multi-day regimens such as GBS (0.4 g/kg x 5 days) yield the same total dose (2 g/kg) as a single high-dose infusion, spread to reduce peak exposure and infusion burden.
IVIG dosing by indication
| Indication | Dose (g/kg) | Schedule | Dosing weight |
|---|---|---|---|
| Primary immunodeficiency (PIID) | 0.4-0.6 | Every 3-4 weeks | IBW / AdjBW |
| Immune thrombocytopenic purpura (ITP) | 1.0 | Single dose; may repeat | IBW / AdjBW |
| Kawasaki disease | 2.0 | Single infusion | Actual weight (pediatric) |
| Guillain-Barre syndrome (GBS) | 0.4 x 5 days | 5 consecutive days (2 g/kg total) | IBW / AdjBW |
| CIDP (induction) | 2.0 | Divided over 2-5 days | IBW / AdjBW |
| CIDP (maintenance) | 1.0 | Every 3 weeks | IBW / AdjBW |
| Myasthenia gravis (exacerbation) | 1.0-2.0 | Over 2-5 days | IBW / AdjBW |
| Multifocal motor neuropathy | 2.0 | Induction; 1.0 maintenance | IBW / AdjBW |
Typical dose ranges per major clinical guideline. Always follow the specific prescription and institutional protocol.
Frequently asked questions
What weight does the IVIG dose calculator use for obese patients?
For patients with a BMI at or above 30, the calculator uses adjusted body weight (AdjBW = IBW + 0.4 x [actual weight - IBW]). This approach, adopted by the Ontario immunoglobulin utilization program and widely cited pharmacy references, provides doses that are clinically equivalent to ABW-based dosing but at lower cost and with a reduced theoretical risk of overdose-related reactions.
What is the Devine formula for ideal body weight?
The Devine formula estimates IBW as: 50.0 kg + 2.3 kg for every inch over 5 feet (men), or 45.5 kg + 2.3 kg for every inch over 5 feet (women). It was originally published in 1974 for drug dosing reference and is still the most commonly used method in pharmacy practice for weight-based drug calculations, including IVIG.
Why is IVIG started slowly and titrated up?
Rapid infusion can trigger acute infusion reactions including flushing, headache, chills, back pain, and blood pressure changes caused by cytokine release and complement activation. Starting at a low rate (typically 30 mL/hr) and increasing in steps every 15-30 minutes gives the body time to equilibrate and gives nurses time to spot and manage early reactions before stopping or slowing the infusion. Most products have manufacturer-specified maximum rates.
What IVIG concentrations are available?
Commercial IVIG products are available as 5% (50 g/L), 10% (100 g/L), and 20% (200 g/L) solutions. Higher concentrations reduce the infusion volume, which can benefit patients with fluid restrictions or those requiring large doses. The 10% formulation is most commonly used in adults. Always consult the specific product monograph for the maximum infusion rate for that product, as they differ.
How is IVIG dosing different from SCIG dosing?
Subcutaneous immunoglobulin (SCIG) replaces the same monthly dose as IVIG but is given in smaller weekly or biweekly volumes at home, eliminating the need for IV access and hospital visits. The monthly IVIG dose in grams is simply divided by the number of weekly infusions. For example, 60 g per month becomes 15 g per week for weekly SCIG. This calculator covers IV infusion only; a separate SCIG calculator should be used for subcutaneous dosing.
Can this calculator be used for paediatric patients?
Paediatric IVIG doses follow the same g/kg principle and the calculator will produce accurate total-dose and volume results when the child's actual weight is entered. However, the Devine IBW formula is designed for adults at least 5 feet tall (around 152 cm). For children below that height the IBW will be negative or nonsensical, so the calculator falls back to actual body weight. Always use actual weight for paediatric patients and confirm with the prescriber and institutional protocol.
What are the main side effects of IVIG?
Common infusion-related reactions include headache, flushing, chills, fatigue, and myalgia; most are rate-related and improve by slowing the infusion. More serious but rare risks include anaphylaxis (especially in patients with selective IgA deficiency), thrombotic events, haemolysis, transfusion-related acute lung injury (TRALI), and aseptic meningitis. Renal function should be monitored, particularly in patients receiving high doses or those with pre-existing renal impairment, as sucrose-containing products can cause osmotic nephropathy.