Electrolyte replacement ladder (K / Mg / Phos)
Level-banded K / Mg / phosphate replacement ladder with IV vs PO route and a renal-impairment caution (Hammond 2019 and standard references).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Electrolyte
- Potassium (mEq/L)
- Serum level
- 2.8
- Route
- IV
Result: K 2.8 mEq/L: 60 mEq IV per ASHP 2019; cap 10 mEq/h peripheral or 20 mEq/h central.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- K 3.0-3.4
- Replace 40 mEq.
- K 2.5-2.9
- Replace 60 mEq.
- K <2.5
- Replace 80 mEq.
- Mg 1.0-1.7
- Replace 2 g MgSO4 IV over 1 h.
- Mg <1.0
- Replace 4 g MgSO4 IV over 1 h.
- Phos 1.6-2.2
- 0.16 mmol/kg per Brown 2006.
- Phos 1.0-1.5
- 0.32 mmol/kg per Brown 2006.
- Phos <1.0
- 0.64 mmol/kg per Brown 2006.
What you enter
- Electrolyte
- Serum level
- Route
- Renal impairment (eGFR < 30 or AKI)
How this is calculated
Hammond DA, King J, et al. Potassium replacement in critically ill patients. Crit Care Nurse. 2019;39(1):e13-e18. Hebert PC, et al. Acute hypomagnesaemia. Acute Care Internal Medicine, Lippincott 2008. Brown KA, et al. Graduated phosphorus replacement. JPEN. 2006;30(3):209-214 (Brown protocol). Read the sources: Hammond 2019 (potassium) ↗, Brown 2006 (phosphorus) ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.