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Estimates the total 24-hour magnesium sulfate dose for a selected IV regimen (loading dose + maintenance infusion) used for prevention and treatment of eclampsia in appropriate preeclampsia/eclampsia settings, consistent with ACOG Practice Bulletin No. 222 (2020) and WHO recommendations. Magnesium sulfate is a high-risk medication: regimen choice depends on clinical setting, route, renal function, monitoring capability, and clinician judgment.
Clinical decision-support tool for qualified healthcare professionals. Results are not a diagnosis and should not replace professional clinical judgment.
Indication: magnesium sulfate is used for the prevention of eclampsia in appropriately selected women with preeclampsia (especially severe preeclampsia) and for the treatment of eclampsia. WHO (2011) recommends magnesium sulfate for prevention of eclampsia in severe preeclampsia and for treatment of eclampsia in preference to other anticonvulsants. Prevention of eclampsia is distinct from acute treatment of an eclamptic seizure; regimens for each setting may differ. This calculator supports an educational estimate of a selected IV regimen's 24-hour total; it is not a mandate for any specific regimen. Regimen choice depends on clinical setting and protocol, route, renal function, monitoring capability, and clinician judgment. Magnesium sulfate is a high-risk medication: administration requires clinical monitoring (patellar reflexes, respiratory rate, urine output, and serum magnesium where available) and is not a routine self-calculation tool. Calcium gluconate should be available to treat magnesium toxicity. This content is educational decision-support, not prescriptive.
Specialty
ObstetricsCategory
Obstetrics & GynecologyDifficulty
Basic
Estimated Time
30 seconds
Version
1.0
Last Updated
2026-08-16
Formula
Keywords
Normal Range
Educational reference only: therapeutic serum magnesium for seizure prophylaxis is approximately 4.8–8.4 mg/dL (2–3.5 mEq/L). Toxicity features are typically associated with loss of patellar reflexes (~10 mg/dL), respiratory depression (~12 mg/dL), and cardiac arrest (~15–17 mg/dL). These are monitoring concepts, not a prescription target.
| Classification | Range |
|---|---|
Typical therapeutic serum magnesium seizure prophylaxis monitoring target (educational) | 4.8–8.4 mg/dL |
Calculates the total 24-hour magnesium sulfate dose for seizure prophylaxis in preeclampsia with severe features or eclampsia from the IV loading dose (4–6 g) and maintenance infusion rate (1–2 g/h) per ACOG (2020).
Selected total 24-hour dose (g) = loading dose (g, given IV over 20-30 minutes) + maintenance rate (g/h) x 24 hours.
Selected IV loading dose in grams (4, 5, or 6 g), added to the 24-hour maintenance total.
Selected maintenance infusion rate in g/h (1 or 2 g/h), multiplied by 24 hours.
The total 24-hour dose equals the loading dose plus 24 × the maintenance rate (e.g., 4 g + 2 g/h = 52 g). The therapeutic serum magnesium range is 4.8–8.4 mg/dL; loss of patellar reflexes occurs near 10 mg/dL and respiratory depression near 12 mg/dL, treated with IV calcium gluconate.
Magnesium sulfate remains the standard of care for seizure prophylaxis in preeclampsia with severe features and for eclampsia, substantially reducing the risk of eclamptic seizures and associated mortality.
A patient with preeclampsia with severe features is started on the standard ACOG regimen: 4 g IV loading dose and a 2 g/h maintenance infusion.
Inputs:
Expected Result: Total 24-hour magnesium sulfate dose 52 g (4 g load + 2 g/h × 24 h); therapeutic serum magnesium 4.8–8.4 mg/dL.
Therapeutic serum magnesium is approximately 4.8–8.4 mg/dL (2–3.5 mEq/L). Levels above 10 mg/dL cause loss of deep tendon reflexes, and respiratory depression occurs near 12 mg/dL.
Most protocols continue therapy for 24 hours after delivery (or 24 hours after the last seizure), after which it is discontinued if severe features have resolved.
Disclaimer: This calculator is intended for educational and clinical decision support purposes only. Magnesium sulfate therapy requires individualized dosing, monitoring for toxicity, and prompt treatment of adverse effects.