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Nephrology · Dosing

Electrolyte repletion and correction

Potassium, magnesium and phosphate repletion with label rate caps; a hypernatremia free-water plan capped to the conventional correction limit; albumin-corrected calcium with hypercalcemia severity, Endocrine Society 2023 treatment steps and IV calcium for hypocalcemia; and unit conversions.

IV K⁺ caps 10 / 20 mEq/hNa⁺ fall capped 0.5 mmol/L/hES 2023 hypercalcemiamg/dL ↔ mmol/LReviewed Oct 2026

1Patient

2Route

3Context

4Levels enter any

Choose the unit your lab reports for Mg and phosphate — SI and conventional normal ranges overlap the deficiency bands, so nothing is dosed until a unit is chosen. Phosphate is not reported in mEq/L: its charge varies with pH, so mEq conversions are unreliable.

How it works

IV potassium: rate and concentration limits
SituationMax rateSource
K⁺ > 2.5, any line10 mEq/h; ≤ 200 mEq/24 hKCl labels (Hospira, ICU Medical)
Peripheral line10 mEq/hBulloch 2024; VUMC; Orlando
Central line + continuous ECG20 mEq/hBulloch 2024; VUMC; Orlando
K⁺ < 2.0 with ECG changes or paralysisup to 40 mEq/h; ≤ 400 mEq/24 h, continuous ECG, frequent K⁺KCl labels

This tool never displays a peripheral rate above 10 mEq/h, a central rate above 20 mEq/h without the 40 mEq/h label criteria, or more than 10 mEq/h without continuous ECG monitoring. The 300 and 400 mEq/L premixes are central-only (label). Peripheral concentrations vary by institution (commonly 10 mEq/100 mL). Potassium chloride concentrate and potassium phosphates are ISMP high-alert medications: use premixed bags and a pump; never give IV push. Potassium from potassium phosphate counts toward the hourly K⁺ limit, and the two should not run at the same time.

Dose ranges by level (published protocols)
K⁺ (mEq/L)VUMC 2025Orlando 2017 (IV)Hamill 1991 (1 h)
3.5–3.940 (3.3–3.9)none ≥ 3.7; 40 (3.4–3.6)—
3.0–3.440–6080 (3.0–3.3)20–30
2.5–2.980120 + call40 (< 3.0)
< 2.5100 (< 2.6)120 + call40

The tool shows these as ranges: 3.5–3.9 → 20–40 mEq (only with a reason: cardiac risk, ongoing losses, digoxin); 3.0–3.4 → 40–80; 2.5–2.9 → 80–120; < 2.5 → 100–120 to start, then continue with rechecks. Bulloch 2024: mild–moderate 10–20 mEq 3–4 times daily; severe (< 2.5) continuous IV at 10 mEq/h peripheral or 20 mEq/h central until normalized. Reduced-dose ranges are the Orlando low-dose protocol (CrCl < 45 mL/min or weight < 40 kg): 3.4–3.6 → 10; 3.1–3.3 → 20; 2.3–3.0 → 30; < 2.3 → 40 mEq + call, recheck 2 h after. VUMC excludes CrCl < 30, AKI and dialysis from its protocol.

Mg (mg/dL)Bulloch 2024VUMC 2025Orlando low-dose
1.6–1.91–2 g over 1–2 h4 g over 4 h (1.3–1.9)1 g (1.5–1.9)
1.0–1.52–4 g over 4–12 h4 g / 8 g (≤ 1.2)2 g (0.9–1.4)
< 1.04–8 g, ≤ 1 g/h8 g over 8 h2 g + call (< 0.9)
Phosphorus (mg/dL)IV dose (K-phos label)K⁺ delivered
1.8 – lower limit (2.5)0.16–0.31 mmol/kg0.23–0.46 mEq/kg
1.0–1.70.32–0.43 mmol/kg0.47–0.63 mEq/kg
< 1.00.44–0.64 mmol/kg0.64–0.94 mEq/kg

Maximum initial or single dose 45 mmol phosphorus (66 mEq K⁺). Actual body weight; consider adjusted weight well above ideal. Doses of ≥ 50 mmol or infusions over 1–3 h have caused death, arrhythmia, hyperkalemia and hypocalcemia (label). The same mmol/kg ranges are used for sodium phosphate in published protocols; the sodium phosphates label gives no repletion dose.

Expected rise and its limits

Potassium: with normal kidney function, 10 mEq raises serum K⁺ about 0.1 mEq/L; below 3.0, about 0.05 mEq/L (Bulloch 2024, Table 2). ICU data: +0.25 mmol/L per 20 mEq measured after infusions (Kruse 1990); +0.5 per 20 mmol at the end of a 1-h infusion, before redistribution (Hamill 1991). Treat the rule as a floor for "how much is still missing", not a prediction. It fails with ongoing losses (diuretics, GI), transcellular shifts (insulin, beta-agonists, alkalosis, refeeding), magnesium depletion, and kidney impairment — where the rise is larger and hyperkalemia is the risk.

Magnesium: up to 50% of an IV dose is excreted in urine and tissue equilibration is slow, so a level drawn soon after infusion overestimates repletion; recheck ≥ 2 h after the infusion (Bulloch 2024) and expect to repeat over days.

Hypernatremia: deficit, sodium change per litre, rate limits
Free-water deficit (L) = TBW × (Na ÷ 140 − 1) ΔNa per 1 L infusate = (infusate Na − serum Na) ÷ (TBW + 1)

TBW = weight × 0.6 (men 65 or younger), 0.5 (women 65 or younger, men over 65), 0.45 (women over 65) — AAFP 2015. Infusate sodium: D5W and water 0, D5 + 0.2% NaCl 34, 0.45% NaCl 77, 0.9% NaCl 154 mmol/L (AAFP 2015). Worked example (Medscape, Adrogué–Madias): an 80-year-old man, 70 kg, Na 165 → TBW 35 L; each litre of D5W lowers Na ≈ 4.6 mmol/L; a 10 mmol/L fall needs ≈ 2.2 L, plus 1–1.5 L of obligatory losses ≈ 153 mL/h over 24 h.

Limits used: chronic or unknown onset ≤ 0.5 mmol/L per hour and ≤ 10 per 24 h (expert opinion as summarized by Feigin 2023; AAFP 2015 gives 8–10 per 24 h; AAFP 2023 accepts up to 12). Developed over hours (known): up to 1 mmol/L per hour (AAFP 2015) and no more than 12 per 24 h (expert opinion: AAFP 2023 SORT B; Medscape acute maximum). Never plan below 145. In shock, isotonic fluid comes first. The formula ignores ongoing losses unless you enter them, and individual responses vary widely — the plan is a starting rate, re-set by measured sodium.

Evidence: no randomized trial supports the 0.5 mmol/L per hour limit in adults. Retrospective cohorts found faster correction (above 0.5 per hour) associated with lower or similar mortality and no neurologic harm (Chauhan 2019; Feigin 2023); a 2025 meta-analysis found no significant overall difference (OR 0.68, 0.38–1.24), with lower mortality in subgroups — admission hypernatremia (OR 0.48), correction within the first 24 h (OR 0.48) and severe hypernatremia (OR 0.55); a 2025 multicenter cohort of 37,913 adults found slow correction associated with lower in-hospital mortality. The tool keeps the conventional cap until trial data settle it.

Calcium: correction, its limits, severity and drugs
Corrected Ca (mg/dL) = Ca + 0.8 × (4 − albumin g/dL)

The formula printed in the zoledronic acid and pamidronate labels. It performs poorly where it matters most: in a 2026 prospective ICU study it flagged 15% of patients whose ionized calcium was low (total calcium alone flagged 63%), and in 691 patients with CKD 3–5 corrected calcium predicted ionized calcium no better than uncorrected calcium (Gauci 2008). Use ionized calcium in critical illness, CKD, acid–base disorders and after large transfusions. Bands and drug thresholds are applied to the corrected value rounded to the 2 decimals shown, in the unit you entered (mmol/L thresholds = mg/dL × 0.25; 1.9 and 3.5 mmol/L are the SfE and ES cutoffs), shown to two decimals. When ionized calcium is entered it sets the band, against your lab’s range or the stated example 1.12–1.32 mmol/L. Drug steps for hypercalcemia appear only with known or suspected malignancy and a PTH that is not high; otherwise the tool shows hydration and specialist referral.

Corrected CaBand (ES 2023)
Above upper reference limit, below 12 mg/dLMild
12–14 mg/dL (3–3.5 mmol/L)Moderate
Above 14 mg/dL (3.5 mmol/L)Severe
DrugDose and limits (source)
Saline1–2 L bolus, then 200–500 mL/h to urine 100–150 mL/h; tailor to cardiac function (ES 2023)
Calcitonin4 units/kg SC/IM every 12 h → 8 units/kg every 12 h → maximum 8 units/kg every 6 h (label); stop by 48–72 h, tachyphylaxis (ES 2023)
Zoledronic acid4 mg IV over ≥ 15 min for corrected Ca ≥ 12; no adjustment if creatinine below 4.5 mg/dL; retreat after ≥ 7 days (label). ES 2023 Table 1 differs: dose adjustment if GFR below 60, infuse over 30–60 min, kidney damage risk especially below 30–35; label for severe renal impairment: only after weighing risks and benefits
Pamidronate60–90 mg (≈ 12–13.5) or 90 mg (above 13.5) over 2–24 h; single dose ≤ 90 mg; creatinine above 3.0 not studied (label); kidney damage risk especially with GFR below 30–35 (ES 2023)
Denosumab120 mg SC days 1, 8, 15, then every 4 weeks for HCM refractory to bisphosphonates (label); hypocalcemia risk with CrCl below 30 or dialysis; ES suggests it over IV bisphosphonates (very low certainty)
GlucocorticoidsCalcitriol-mediated: hydrocortisone 200–400 mg IV/day for 3–5 days, or prednisone 60 mg/day for 10 days (ES 2023 Table 1)

IV calcium: 10% calcium gluconate holds 9.3 mg elemental calcium per mL; 10% calcium chloride holds 27 mg per mL (about 3 times as much). Gluconate: 1,000–2,000 mg per dose, ≤ 200 mg/min, infusion 5.4–21.5 mg/kg/h, lowest dose with kidney impairment (label). Chloride: 200–1,000 mg via a central or deep vein at ≤ 1 mL/min (label). SfE 2016 defines severe hypocalcemia as below 1.9 mmol/L or symptomatic, and advises against large-volume calcium infusions in end-stage kidney disease or dialysis — the tool then shows only the lowest bolus.

Unit conversions
Calcium: mmol/L = mg/dL × 0.25 · Albumin: g/L = g/dL × 10 · Creatinine: µmol/L = mg/dL × 88.4 Mg: mmol/L = mg/dL × 0.4114 · mEq/L = mmol/L × 2 Phosphorus: mmol/L = mg/dL × 0.3229 K⁺: mmol/L = mEq/L

Magnesium sulfate heptahydrate: 1 g = 8.12 mEq = 4.06 mmol Mg. Potassium phosphates: 3 mmol P + 4.4 mEq K⁺ per mL. Sodium phosphates: 3 mmol P + 4 mEq Na⁺ per mL. Bands are applied to the mg/dL value rounded to one decimal, and that value is shown.

Sources

  1. Potassium Chloride for Injection Concentrate, USP — prescribing information, Hospira (rev. 01/2026); Potassium Chloride Injection (premixed, highly concentrated) — prescribing information, ICU Medical (label rev. 06/2018; DailyMed listing 06/2026). DailyMed.
  2. Potassium Phosphates Injection — prescribing information, Hospira (2025), sections 2.1–2.2, 4, 5.1, 8.6. DailyMed.
  3. Magnesium Sulfate Injection — prescribing information, Hospira 50% (2026) and Civica (2026): rate 150 mg/min, maximum 20 g per 48 h in severe renal insufficiency, reflex loss above 4 mEq/L. DailyMed.
  4. Potassium chloride extended-release tablets (Klor-Con M) — prescribing information, dosage and administration.
  5. Institute for Safe Medication Practices. ISMP List of High-Alert Medications in Acute Care Settings (2018): potassium chloride for injection concentrate, potassium phosphates injection, magnesium sulfate injection.
  6. Bulloch MN, Cardinale-King M, Cogle S, et al. Correction of electrolyte abnormalities in critically ill patients. Intensive Care Res 2024;4:19–37. doi:10.1007/s44231-023-00054-3 — Table 2 (dosing, rates, expected K⁺ rise, monitoring).
  7. Orlando Health Surgical Critical Care. Adult electrolyte replacement protocols, standard and low-dose (approved 2001, revised 09/2017). surgicalcriticalcare.net.
  8. Vanderbilt University Medical Center Burn Center. Burn electrolyte replacement guideline (revised April 2025).
  9. Hamill RJ, Robinson LM, Wexler HR, Moote C. Efficacy and safety of potassium infusion therapy in hypokalemic critically ill patients. Crit Care Med 1991;19:694–9. doi:10.1097/00003246-199105000-00016
  10. Kruse JA, Carlson RW. Rapid correction of hypokalemia using concentrated intravenous potassium chloride infusions. Arch Intern Med 1990;150:613–7.
  11. Huang CL, Kuo E. Mechanism of hypokalemia in magnesium deficiency. J Am Soc Nephrol 2007;18:2649–52. doi:10.1681/ASN.2007070792
  12. Drew BJ, Ackerman MJ, Funk M, et al. Prevention of torsade de pointes in hospital settings: AHA/ACCF scientific statement. J Am Coll Cardiol 2010;55:934–47. doi:10.1016/j.jacc.2010.01.001 — magnesium sulfate 2 g IV as first-line therapy for TdP irrespective of the serum magnesium level.
  13. Wigginton JG, Agarwal S, Bartos JA, et al. Part 9: Adult advanced life support: 2025 AHA Guidelines for CPR and ECC. Circulation 2025;152(16 Suppl 2):S538–77 — immediate unsynchronized shock for sustained polymorphic VT (COR 1, LOE B-NR); magnesium may be considered for recurrent polymorphic VT with long QT (COR 2b); no magnesium dose.
  14. O'Brien B, Campbell NG, Allen E, et al. Potassium supplementation and prevention of atrial fibrillation after cardiac surgery: the TIGHT K randomized clinical trial. JAMA 2024;332:979–88. doi:10.1001/jama.2024.17888
  15. da Silva JSV, Seres DS, Sabino K, et al. ASPEN consensus recommendations for refeeding syndrome. Nutr Clin Pract 2020;35:178–95. doi:10.1002/ncp.10474 — Table 6 (adults): 100–150 g dextrose or 10–20 kcal/kg for 24 h; electrolytes every 12 h for 3 days in high-risk patients; thiamin 100 mg before feeding.
  16. Matthews-Rensch K, Blackwood K, Lawlis D, et al. The Australasian Society of Parenteral and Enteral Nutrition: consensus statements on refeeding syndrome. Nutr Diet 2025;82:128–42. doi:10.1111/1747-0080.70003 §3.4.1: studies used thiamin 100–300 mg; dose and route by clinical judgement.
  17. Labcorp. SI unit conversion table: calcium mg/dL × 0.25 = mmol/L; magnesium mg/dL × 0.4114 = mmol/L; phosphorus mg/dL × 0.323 = mmol/L; albumin g/dL × 10 = g/L; creatinine mg/dL × 88.4 = µmol/L.
  18. Feigin E, Feigin L, Ingbir M, et al. Rate of correction and all-cause mortality in patients with severe hypernatremia. JAMA Netw Open 2023;6:e2335415. doi:10.1001/jamanetworkopen.2023.35415 — states the expert-opinion limit (0.5 mmol/L/h or 10 mmol/L/day) and its weak evidence base.
  19. Braun MM, Barstow CH, Pyzocha NJ. Diagnosis and management of sodium disorders: hyponatremia and hypernatremia. Am Fam Physician 2015;91:299–307 — water-deficit formula, total-body-water fractions, 0.5 mEq/L/h (chronic) and 1 mEq/L/h (rapid onset), target 145, fluid sodium contents.
  20. Miller NE, Rushlow D, Stacey SK. Diagnosis and management of sodium disorders: hyponatremia and hypernatremia. Am Fam Physician 2023;108:476–86 — SORT: up to 12 mEq/L per 24 h; do not re-raise sodium after overshoot.
  21. Lukitsch I. Hypernatremia treatment and management. Medscape (updated 2016) — Adrogué–Madias change-in-sodium formula and worked example (80-year-old man, 70 kg, Na 165 mmol/L).
  22. Adrogué HJ, Madias NE. Hypernatremia. N Engl J Med 2000;342:1493–9. doi:10.1056/NEJM200005183422006 (original source of the formula; not re-opened this session).
  23. Chauhan K, Pattharanitima P, Patel N, et al. Rate of correction of hypernatremia and health outcomes in critically ill patients. Clin J Am Soc Nephrol 2019;14:656–63. doi:10.2215/CJN.10640918
  24. Chacon-Palma G, Teixeira JP, Litvinovich I, et al. Relationship between rate of hypernatremia correction and outcomes in hospitalized patients. Kidney360 2025;6:1305–16. doi:10.34067/KID.0000000785
  25. Kitisin N, Raykateeraroj N, Hikasa Y, et al. Systematic review and meta-analysis of the treatment of hypernatremia in adult hospitalized patients. J Crit Care 2025;87:155012. doi:10.1016/j.jcrc.2024.155012
  26. Sonani B, Al-Dhahir MA. Hypernatremia. StatPearls (updated 08/2023) — isotonic fluid first in shock; enteral water preferred; monitor ongoing losses.
  27. El-Hajj Fuleihan G, Clines GA, Hu MI, et al. Treatment of hypercalcemia of malignancy in adults: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2023;108:507–28. doi:10.1210/clinem/dgac621 — severity bands; recommendations 1–8; Table 1 regimens. Table 1 renal comments: zoledronic acid dose adjustment if GFR below 60; kidney damage risk with both bisphosphonates especially below 30–35 mL/min.
  28. Zoledronic Acid Injection (4 mg/5 mL) — prescribing information, Mylan Institutional (DailyMed 02/2026), sections 1.1, 2.1, 5.2, 8.6: hypercalcemia of malignancy, corrected Ca ≥ 12 mg/dL; 4 mg over ≥ 15 min; no adjustment with serum creatinine below 4.5 mg/dL; retreat after ≥ 7 days.
  29. Pamidronate Disodium Injection — prescribing information, Hospira (DailyMed 05/2026): 60–90 mg (corrected Ca ≈ 12–13.5 mg/dL) or 90 mg (above 13.5) over 2–24 h; single dose ≤ 90 mg; serum creatinine above 3.0 mg/dL not studied.
  30. Xgeva (denosumab) — prescribing information, Amgen (DailyMed 07/2026), sections 1.3, 2.4, 5.3, 8.6: 120 mg SC every 4 weeks plus days 8 and 15 for hypercalcemia of malignancy refractory to bisphosphonates; hypocalcemia risk with CrCl below 30 or dialysis.
  31. Miacalcin (calcitonin salmon) injection — prescribing information, Mylan Institutional (DailyMed 06/2026), section 2.2: 4 units/kg every 12 h, up to 8 units/kg every 6 h.
  32. Calcium Gluconate Injection — prescribing information, Amneal (DailyMed 06/2026): 9.3 mg (0.465 mEq) elemental Ca per mL; adult bolus 1,000–2,000 mg, infusion 5.4–21.5 mg/kg/h, ≤ 200 mg/min; lowest dose in renal impairment.
  33. Calcium Chloride Injection 10% — prescribing information, PAI Pharma (rev. 04/2026): 27 mg (1.4 mEq) elemental Ca per mL; 200–1,000 mg adult; central or deep vein; ≤ 1 mL/min.
  34. Turner J, Gittoes N, Selby P; Society for Endocrinology Clinical Committee. Emergency management of acute hypocalcaemia in adult patients. Endocr Connect 2016;5:G7–G8 (addendum 2019;8:X1).
  35. Özdemir E, Yılmaz T, Düzenci D. Limited diagnostic utility of albumin-corrected calcium in the intensive care unit. PLoS One 2026;21:e0354233. doi:10.1371/journal.pone.0354233
  36. Gauci C, Moranne O, Fouqueray B, et al. Pitfalls of measuring total blood calcium in patients with CKD. J Am Soc Nephrol 2008;19:1592–8. doi:10.1681/ASN.2007040449
  37. Almuradova E, Cicin I. Cancer-related hypercalcemia and potential treatments. Front Endocrinol 2023;14:1039490 — PTH/PTHrP/1,25-dihydroxyvitamin D sequence; hemodialysis in advanced kidney disease.
  38. English KA, Lines KE, Thakker RV. Genetics of hereditary forms of primary hyperparathyroidism. Hormones 2024;23:3–14 — FHH urinary calcium/creatinine clearance ratio below 0.01.
  39. Gurram PR, Castillo NE, Esquer Garrigos Z, et al. An unusual cause of hypercalcemia (histoplasmosis). Am J Med 2020;133:e659–62 — exclude infection before steroids in granulomatous hypercalcemia.
  40. Sheehan MT, Wermers RA, Jatoi A, et al. Evaluation of diagnostic workup and etiology of hypercalcemia of malignancy. J Endocr Soc 2021;5:bvab157 — calcium reference limits 8.2–8.5 to 10.2–10.5 mg/dL.
  41. Kidney Disease: Improving Global Outcomes (KDIGO) CKD-MBD Update Work Group. KDIGO 2017 clinical practice guideline update for the diagnosis, evaluation, prevention, and treatment of CKD-MBD. Kidney Int Suppl 2017;7:1–59. doi:10.1016/j.kisu.2017.04.001
  42. Kardalas E, Paschou SA, Anagnostis P, et al. Hypokalemia: a clinical update. Endocr Connect 2018;7:R135–46 — 0.9% saline preferred to 5% glucose as the IV diluent.
  43. Hansen BA, Bruserud Ø. Hypomagnesemia in critically ill patients. J Intensive Care 2018;6:21. doi:10.1186/s40560-018-0291-y — magnesium deficiency impairs PTH secretion and causes PTH resistance.

Educational reference only — not a substitute for clinical judgment, institutional protocols, or specialist advice. Calculations run in your browser; nothing you enter is sent or stored.