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, and a titrated infusion schedule. Dosing weight follows the Ontario Regional Blood Coordinating Network IGUM rule: adjusted body weight for adults who meet the height and weight criteria, and actual body weight for everyone else, including paediatric patients. Switch between metric and imperial.
Formula
Worked example
A 100 kg male, 175 cm tall. He is over 152.4 cm and over 50 kg, so the adjusted-weight rule applies. IBW = 50 + 2.3 x (68.9 - 60) = 70.5 kg. Dosing weight = 70.5 + 0.4 x (100 - 70.5) = 82.3 kg. Prescribed 2 g/kg for CIDP over 2 days: total dose = 82.3 x 2 = 164.6 g. Daily dose = 82.3 g. At 10% concentration: 823 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, around 5 hours per day. A 16 kg, 100 cm child is below the height criterion, so actual weight is used: 2 g/kg x 16 kg = 32 g.
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 in obese patients using actual body weight would give substantially more immunoglobulin than the intended pharmacological effect requires, because IgG distributes mainly in lean tissue and plasma volume. The Ontario Regional Blood Coordinating Network IGUM dose calculator therefore sets the dosing weight to an adjusted body weight, AdjBW = IBW + 0.4 x (actual - IBW), for patients at least 152.4 cm tall who weigh more than 50 kg (male) or 45.5 kg (female). Patients who do not meet those height and weight criteria, including paediatric patients, are dosed on actual body weight, as is any patient whose actual weight is already below IBW. Plain ideal body weight is never used as the dosing weight; doing so would under-dose. This calculator applies the Devine formula to derive IBW, then applies that rule.
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 adjusted-weight and actual-weight dosing in overweight IVIG recipients show similar clinical efficacy with measurable cost savings when adjusted weight is used. The Ontario provincial immunoglobulin utilization program mandates the adjusted-weight calculator for every patient with a BMI above 30, and recommends it for all adults meeting the height and weight criteria. Using actual body weight when it falls below IBW, and for short or paediatric patients, avoids under-dosing: a 16 kg child dosed on a Devine IBW would receive a small fraction of the intended immunoglobulin. 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. Selecting an indication applies that total course dose in g/kg; choose "Enter dose manually" to type any other value. The presets 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. Multi-day regimens such as GBS (0.4 g/kg x 5 days) are entered as the 2 g/kg total with 5 days, and the calculator divides it into the daily dose.
IVIG dosing by indication
| Indication | Dose (g/kg) | Schedule | Dosing weight |
|---|---|---|---|
| Primary immunodeficiency (PIID) | 0.4-0.6 | Every 3-4 weeks | AdjBW / actual |
| Immune thrombocytopenic purpura (ITP) | 1.0 | Single dose; may repeat | AdjBW / actual |
| 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) | AdjBW / actual |
| CIDP (induction) | 2.0 | Divided over 2-5 days | AdjBW / actual |
| CIDP (maintenance) | 1.0 | Every 3 weeks | AdjBW / actual |
| Myasthenia gravis (exacerbation) | 1.0-2.0 | Over 2-5 days | AdjBW / actual |
| Multifocal motor neuropathy | 2.0 | Induction; 1.0 maintenance | AdjBW / actual |
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?
It follows the Ontario Regional Blood Coordinating Network IGUM rule. For a patient at least 152.4 cm tall who weighs more than 50 kg (male) or 45.5 kg (female), the dosing weight is the adjusted body weight: AdjBW = IBW + 0.4 x (actual weight - IBW). Ontario mandates this for every patient with a BMI above 30 and recommends it for all adults meeting those criteria. Anyone below the height or weight criteria, including paediatric patients, and anyone whose actual weight is already below IBW, is dosed on actual body weight. Plain ideal body weight is never used on its own.
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?
Yes. Paediatric IVIG doses follow the same g/kg principle. The Devine IBW formula is designed for adults at least 5 feet tall (152.4 cm) and returns nonsensical values below that height, so, in line with the Ontario IGUM rule for patients under 18 who do not meet the height and weight criteria, the calculator uses actual body weight whenever height is under 152.4 cm or weight is at or below 50 kg (male) / 45.5 kg (female). A 16 kg child prescribed 2 g/kg for Kawasaki disease therefore gets 32 g. Always confirm the dose 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.