ElectrolyteRx is intended solely for use by licensed healthcare professionals as a verification support tool, including for the hyponatremia/hypernatremia correction-rate and hyperkalemia management modules. It does not replace independent clinical judgment, current institutional protocol, nephrology/endocrinology consultation, or frequent laboratory monitoring during active correction.
Payne formula (1973). Estimates total calcium as it would appear if albumin were normal — does not measure ionized calcium.
Enter values and click Calculate.
Corrected Sodium for Hyperglycemia
Hyperglycemia causes osmotic water shift that lowers measured sodium independent of true total-body sodium/water status. Two correction factors are in common use — shown side by side rather than picking one silently.
Enter values and click Calculate.
Free Water Deficit
Estimates the water deficit driving hypernatremia, based on total body water. Does not itself set a safe correction rate — see the Hypernatremia Rate Limit tab to translate this into a rate.
Enter values and click Calculate.
Maintenance IV Fluid Rate — Holliday-Segar
Weight-based maintenance fluid rate (the "4-2-1 rule"), derived from Holliday & Segar, Pediatrics 1957. Originally a pediatric formula; commonly extrapolated to adults but many adult protocols instead use a flat 25–30 mL/kg/day — see the note below before applying in adults.
Common representative dosing bands, not a single universal standard — unlike the Payne, Holliday-Segar, or Katz/Hillier formulas above, exact replacement doses and infusion rates vary meaningfully by institution. Confirm against your institutional protocol, particularly infusion-rate limits and cardiac-monitoring requirements for IV replacement.
Potassium
Serum K⁺
Typical Replacement
3.0–3.4 mEq/L
40–60 mEq PO (divided doses; GI upset common with single large doses)
2.5–2.9 mEq/L
60–80 mEq, PO and/or IV combined
<2.5 mEq/L or symptomatic (arrhythmia, significant weakness)
IV KCl, typically 10 mEq/hr peripheral line (up to ~20 mEq/hr via central line with continuous cardiac monitoring) — institutional max infusion rates vary; recheck level after each 20–40 mEq infused
Concentration/rate limits — label vs. common institutional practiceThe current FDA label for KCl injection concentrate sets a single ceiling regardless of line type: ≤10 mEq/hr for routine repletion, up to 40 mEq/hr with continuous cardiac monitoring for urgent/severe hypokalemia (K⁺ <2.0 with ECG changes or paralysis), 24-hour max 200 mEq — it does NOT itself distinguish peripheral from central administration. The widely-followed peripheral-vs-central split (≤10 mEq/100 mL and ≤10 mEq/hr peripheral; up to ~20 mEq/100 mL and 20–40 mEq/hr central with continuous cardiac monitoring) is a common, more conservative institutional/nursing-reference convention layered on top of the label, not itself a numbered FDA or ISMP standard — a specific current ISMP document with these exact peripheral/central numbers could not be located. Confirm your own institutional policy; KCl is an ISMP-designated high-alert medication regardless of route.
Magnesium
Serum Mg²⁺
Typical Replacement
1.0–1.5 mg/dL, asymptomatic
1–2 g MgSO₄ IV over 1–2 hr
<1.0 mg/dL or symptomatic (seizure, torsades de pointes)
1–2 g MgSO₄ IV push over several minutes for torsades; otherwise 2 g IV over 1 hr, then reassess — consider a slower maintenance infusion for ongoing severe deficit
Renal impairmentReduce magnesium repletion dose and infusion rate in significant renal impairment — magnesium is renally cleared and accumulates; monitor levels more frequently.
Concentration/rate limits (FDA label)The 50% MgSO₄ stock solution must NEVER be injected IV undiluted — it is only given undiluted by the IM route. For IV use (push or infusion), it must first be diluted to a concentration of ≤20%; verify the pharmacy-prepared bag/syringe concentration is ≤20% before infusing peripherally or centrally. Maximum IV push rate is ≤150 mg/min (relevant to the torsades/seizure bolus above); for continuous maintenance infusion, the label itself notes 1–2 g/hour is commonly used in practice rather than stating a separate hard ceiling.
Phosphate
Serum Phosphate
Typical Replacement
2.0–2.5 mg/dL, asymptomatic
Oral phosphate (e.g., potassium or sodium phosphate) — divided doses, GI tolerance limits total
1.0–1.9 mg/dL
IV phosphate 15–30 mmol over 4–6 hr
<1.0 mg/dL or symptomatic
IV phosphate 0.25–0.5 mmol/kg over 4–6 hr — monitor calcium (risk of hypocalcemia/precipitation with concurrent calcium-containing fluids) and recheck level after infusion
Salt selectionChoose potassium vs. sodium phosphate based on the patient's potassium status — do not add a potassium-containing phosphate salt to a hyperkalemic or renally-impaired patient without checking K⁺ first.
Peripheral infusion rate (FDA label)Current potassium phosphate injection labeling specifies a peripheral infusion rate of approximately 6.8 mmol phosphorus/hr (≈10 mEq potassium/hr), with ECG monitoring recommended above that rate, and a maximum single/initial dose of 45 mmol phosphorus. A current FDA label specifically for sodium phosphate injection with its own distinct rate limit was not located — use the potassium phosphate rate as the more conservative reference if using the sodium salt, and confirm against your institutional protocol.
Calcium
Corrected Serum Calcium
Typical Replacement
7.5–8.5 mg/dL, asymptomatic
Oral calcium carbonate or citrate ± vitamin D — address the underlying cause (vitamin D deficiency, hypomagnesemia, hypoparathyroidism)
<7.5 mg/dL or symptomatic (tetany, seizures, QTc prolongation)
Calcium gluconate 1-2 g (10-20 mL of 10%) IV over 10-20 minutes, followed by a continuous infusion if ongoing repletion is needed (e.g., post-thyroidectomy hypoparathyroidism) — check ionized calcium and magnesium (correct hypomagnesemia first if present, as it blunts PTH response and repletion will not hold otherwise)
This is NOT the same indication or rate as the Hyperkalemia tab's calcium doseThe Hyperkalemia Management tab's calcium gluconate 1000 mg IV over at least 5 minutes (per the FDA label's 200 mg/min adult bolus rate cap) is for EMERGENT cardiac membrane stabilization in hyperkalemia — a different, faster protocol than routine symptomatic hypocalcemia repletion above. Do not confuse the two indications.
Concentration/rate limits (FDA label, calcium gluconate)Bolus dilution 10-50 mg/mL; continuous-infusion dilution 5.8-10 mg/mL. Maximum infusion rate 200 mg/min in adults, 100 mg/min in pediatric/neonatal patients. The label does not state a separate peripheral-specific concentration cap distinct from these dilution ranges, but does warn of extravasation/tissue necrosis — secure IV access is required regardless of route. (Calcium chloride, in contrast, requires central/deep-vein administration only per its own current label — see the Hyperkalemia tab for that distinction.)
⚠ Hyperkalemia Emergency Management
Stratifies urgency and sequences treatment. Per current nephrology consensus (Palmer & Clegg, Nephrol Dial Transplant 2024), the ECG is not reliable — it can remain normal despite severe hyperkalemia, so a normal ECG must never be used to defer treatment at K⁺ >6.0 mEq/L. Conversely, ANY ECG change (even at a lower K⁺, especially if the level rose rapidly) mandates emergent treatment regardless of the lab value.
Enter serum potassium and click Assess.
Step 1 — Confirm Hypotonic Hyponatremia
Before using volume status or urine studies to find the CAUSE, confirm this is actually hypotonic (true, water-excess) hyponatremia. Hyperglycemia (translocational) and pseudohyponatremia (severe hyperlipidemia/hyperproteinemia, with an older ion-selective-electrode assay) can produce a low measured sodium that is NOT hypotonic — routing these into the volume-status/SIADH tree below would misclassify them.
Enter serum osmolality (preferred) or glucose, then click Check Tonicity, before proceeding to Step 2.
Step 2 — Assess Volume Status
Once hypotonicity is confirmed in Step 1, the volume-status exam is the next branch point for diagnosing the CAUSE of hyponatremia — this is separate from the correction-RATE safety check in the Hyponatremia Rate Limit tab. Assess before checking urine studies below.
Urine sodium and osmolality narrow the differential once volume status is assessed. Urine Na <30 mEq/L generally identifies both hypovolemic AND hypervolemic hyponatremia (kidneys appropriately retaining sodium); Urine Na >30 mEq/L in a clinically euvolemic patient, with urine osmolality >100 mOsm/kg, supports SIADH.
Select volume status and enter urine studies, then click Interpret.
Etiology & Treatment by Category
Hypovolemic
Renal losses (urine Na typically >30 mEq/L): diuretics — especially thiazides; mineralocorticoid deficiency/primary adrenal insufficiency; salt-wasting nephropathy; cerebral salt wasting (neurocritical care context, distinguished from SIADH mainly by volume status). Extrarenal losses (urine Na typically <30 mEq/L): GI losses (vomiting, diarrhea), burns, third-spacing (pancreatitis, ileus). Treatment: isotonic (0.9%) saline.
Euvolemic
SIADH is the most common cause of hyponatremia overall. Diagnostic criteria: hypotonic hyponatremia, clinical euvolemia, urine osmolality >100 mOsm/kg, urine sodium usually >30 mEq/L (cited as >30-40 mEq/L across sources — not a single precise cutoff), normal thyroid and adrenal function, and no diuretic use. Causes: malignancy (small-cell lung cancer is the classic association), CNS disorders (stroke, hemorrhage, infection, trauma), pulmonary disease (pneumonia, TB, positive-pressure ventilation), and drugs (SSRIs, carbamazepine/oxcarbazepine, cyclophosphamide, vincristine/vinblastine, antipsychotics, MDMA, NSAIDs, opioids). Treatment: fluid restriction <1 L/day is first-line, tightened to <500 mL/day if the urine-to-serum electrolyte ratio (urine [Na+K]/serum Na) is >1 — a ratio this high predicts fluid restriction alone is likely to fail at looser targets. Salt tablets and/or a loop diuretic (to blunt urine-concentrating ability) are used adjunctively. 3% saline is used for severe/symptomatic hyponatremia regardless of cause (see the 3% Saline tab). Tolvaptan (vasopressin receptor antagonist): FDA boxed warning — initiate/reinitiate only in a hospital setting with close sodium monitoring (correction >12 mEq/L/24h risks osmotic demyelination); do NOT use for more than 30 days (liver injury risk); avoid in patients with underlying liver disease, including cirrhosis.
Primary polydipsia — urine osmolality <100 mOsm/kg is the key differentiator from SIADH; treatment is water restriction and addressing the underlying psychiatric/compulsive drinking behavior, not the SIADH pharmacologic approach.
Low dietary solute intake ("tea and toast," beer potomania) — limited dietary osmoles restrict the kidney's free-water excretion capacity; urine osmolality and sodium are often (but not reliably) low. High risk of overly rapid auto-correction once normal eating/refeeding resumes — recheck sodium frequently.
Hypothyroidism — typically only severe/myxedema causes clinically significant hyponatremia; treat with thyroid hormone replacement.
Secondary adrenal insufficiency — cortisol deficiency removes a tonic inhibitor of ADH release, producing an SIADH-like picture that resolves with glucocorticoid replacement, not fluid restriction — check morning cortisol/ACTH stimulation if suspected, especially with a history of chronic steroid use or pituitary disease.
Hypervolemic
Heart failure, cirrhosis, nephrotic syndrome, advanced CKD — mechanism is effective arterial blood volume depletion (reduced cardiac output, splanchnic vasodilation in cirrhosis, reduced GFR) triggering non-osmotic ADH release despite total-body volume/sodium excess. Urine Na is usually <30 mEq/L except in advanced CKD. Treatment: sodium AND fluid restriction, loop diuretics, and treatment of the underlying disease — NOT isotonic saline, which would worsen volume overload. Tolvaptan is FDA-labeled for hypervolemic hyponatremia including heart failure, but current labeling advises avoiding it in patients with underlying liver disease, including cirrhosis specifically.
⚠ Severe Symptomatic Hyponatremia — 3% NaCl Bolus Protocol
For severe symptoms (seizures, obtundation, delirium, coma) with confirmed hypotonic hyponatremia — bolus 3% NaCl, repeated as needed, is favored over a calculated continuous infusion as the first-line approach for hyponatremic encephalopathy. Two distinct protocols are in use — this is NOT one blended regimen, select which one your institution follows: the US trial-based approach (Baek et al., JAMA Intern Med 2021 SALSA trial) uses 100 mL over 10 minutes; the European Hyponatraemia Guideline (Spasovski et al., 2014, on behalf of the Hyponatraemia Guideline Development Group — paywalled, not read directly in this build; figure corroborated by multiple secondary clinical references) recommends 150 mL over 20 minutes, up to 3 doses. A 2025 systematic review/meta-analysis (3 studies, 290 patients) found bolus and continuous infusion equally safe and effective, with no significant difference in overcorrection, but did not itself resolve which bolus volume/duration is preferred.
For mild-to-moderate symptoms (fatigue, nausea, confusion without severe encephalopathy) or for planning ongoing correction after the initial bolus-phase target has been reached, a slow continuous infusion using the sodium deficit/Adrogué-Madias formula is used instead of repeated boluses. This is a starting-point calculation, not a prediction you can trust unmonitored — the formula assumes no ongoing sodium or water loss, which is frequently wrong in practice (see the worked example below). This tab now enforces the applicable 24h correction ceiling directly — it will not calculate an infusion for a rise beyond what remains allowable.
Enter values and click Calculate.
⚠ Hyponatremia Correction Rate Limit
Overly rapid correction of chronic/subacute hyponatremia risks osmotic demyelination syndrome (ODS). This module tracks the rise against the applicable ceiling and flags overcorrection. The ceiling differs between the first 24 hours of treatment and every 24-hour period after that — select which window this reading falls in.
Enter values and click Calculate.
Step 1 — Interpret Urine Osmolality
Urine osmolality is the key first branch point for diagnosing the CAUSE of hypernatremia — separate from the Free Water Deficit and Hypernatremia Rate Limit tabs, which handle treatment math once the cause is known. This interpretation only applies to confirmed hypotonic polyuria with paired plasma data — enter both below before interpreting.
Confirm polyuria, enter paired plasma and urine osmolality, then click Interpret.
Step 2 — Desmopressin (DDAVP) Challenge Test
If Step 1 suggests diabetes insipidus (inappropriately dilute urine), this test distinguishes central from nephrogenic DI. This must be performed under direct medical supervision in a monitored inpatient or closely observed setting — oral/intranasal desmopressin absorption is too unpredictable, and hyponatremic complications are possible, for this to be run as an unsupervised outpatient test. Where available, prefer referral to endocrinology and a copeptin-based assay over the classic water-deprivation/desmopressin test (see the evolving-reference-standard note below). Protocol if performed (UK EMC desmopressin nasal spray SPC): after water deprivation, restrict fluids from 1 hour before to 8 hours after the dose; empty the bladder at dosing; discard the first hour of urine; measure urine osmolality before dosing and again at 2 and 4 hours post-dose.
Enter both values and click Calculate.
Cutoff varies across sources — and the reference standard is evolving>50% rise for central DI and <15% for complete nephrogenic DI are the most commonly cited cutoffs, but a 2024 retrospective proposed a refined ≥54% threshold (small nephrogenic-DI cohort, limited generalizability), and partial responses in the 15-50% range are genuinely ambiguous (partial central DI and partial nephrogenic DI overlap here). Contemporary literature (copeptin-based testing, e.g., Fenske et al. NEJM 2018; Winzeler et al. Lancet 2019) argues copeptin assays are more accurate and are displacing the classic water-deprivation/desmopressin test as the reference standard where available.
Etiology Reference
Central Diabetes Insipidus
Causes: idiopathic, head trauma, pituitary/hypothalamic surgery, cranial neoplasm (craniopharyngioma, germinoma, metastases), infiltrative disease (sarcoidosis, histiocytosis), ischemic/hypoxic encephalopathy. Triphasic response after pituitary surgery: transient DI from axonal shock (first ~5-7 days) → SIADH-like antidiuresis around day 4-5 from uncontrolled release of stored ADH by degenerating axons → permanent DI if >80-90% of ADH-secreting neurons are destroyed. Treatment: desmopressin, FDA-labeled at 10-40 mcg/day intranasal, single or divided 2-3 times daily, individualized to urine output/nocturia.
Nephrogenic Diabetes Insipidus
Lithium is the leading acquired cause (reduced AQP2 channel expression in collecting-duct principal cells with chronic use). Other causes: hypercalcemia, hypokalemia, congenital AVPR2/AQP2 mutations, post-obstructive uropathy, and drugs including foscarnet and demeclocycline. Treatment: thiazide diuretic + low-sodium/low-protein diet, sometimes with amiloride (particularly useful in lithium-induced NDI — blocks ENaC, the channel lithium uses to enter principal cells) or an NSAID as adjunct. The thiazide "paradox": mild volume contraction increases proximal sodium/water reabsorption, delivering less water to the (defective) collecting duct — reducing urine output independent of the underlying concentrating defect.
Iatrogenic (hypertonic saline or sodium bicarbonate administration — common in cardiac arrest/severe acidosis management), primary hyperaldosteronism, rare accidental/intentional salt poisoning (including improperly mixed infant formula — a real, documented pediatric entity).
Once the cause is identifiedFor non-DI causes and as a general framework, use the Free Water Deficit tab to estimate the water deficit, and the Hypernatremia Rate Limit tab to keep correction within a safe rate — this workup tab does not duplicate that math.
⚠ Hypernatremia Correction Rate Limit
Overly rapid correction of hypernatremia risks cerebral edema. This module checks a planned correction against the commonly-used ceiling.
Enter values and click Calculate.
References
Payne RB, Little AJ, Williams RB, Milner JR. Interpretation of serum calcium in patients with abnormal serum proteins. Br Med J. 1973;4(5893):643-646. (Corrected calcium formula: Corrected Ca (mg/dL) = Measured Ca + 0.8 × [4.0 − Albumin g/dL])
Das M, Baruah A. Total Versus Ionized Calcium: Valid Index of Calcium Status in Critically Ill Patients. Arch Pathol Lab Med. 2026 (online ahead of print). (Albumin-corrected calcium correlates poorly with measured ionized calcium in ICU patients — the correction is an estimate, not a substitute for ionized calcium when precision matters)
Katz MA. Hyperglycemia-induced hyponatremia — calculation of expected serum sodium depression. N Engl J Med. 1973;289(16):843-844. (Classic 1.6 mEq/L Na decrease per 100 mg/dL glucose rise above 100 mg/dL)
Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999;106(4):399-403. (Experimentally derived correction factor of 2.4 mEq/L per 100 mg/dL — found to be more accurate overall than 1.6; noted the relationship is nonlinear, with 1.6 performing adequately below glucose 400 mg/dL and a steeper ~4.0 factor fitting better above 400 mg/dL)
Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-832. (Original 4-2-1 weight-based maintenance fluid formula)
Rout P, Afzal M. Hyponatremia. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; updated 2026 Jun 19. NBK470386. (First-24h hyponatremia correction ceiling: European Clinical Practice Guidelines set an upper limit of 10 mEq/L; the US Expert Panel Recommendations do not themselves set a hard upper limit for this phase; traditional teaching cites 10-12 mEq/L/24h; total body water fraction of 0.6 for men/children, 0.5 for women/older adults)
Ball S. Hyponatremia. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com; 2018 Jun 6. NBK279136. (First-24h ceiling 10 mmol/L with a pragmatic target of 6-8 mmol/L; after the first 24 hours, ceiling of no more than 8 mmol/L per subsequent 24h period — the two-tier ceiling used in the Hyponatremia tab is sourced to this chapter)
Sonani B, Al-Dhahir MA. Hypernatremia. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; updated 2023 Aug 24. NBK441960. (Hypernatremia correction ceiling of 10-12 mEq/L/24h, confirming the Kidney Int Rep/Cureus sourcing below; free water deficit total body water fraction of 0.6 men / 0.5 women with no age adjustment stated — a simpler split than the Hyponatremia StatPearls chapter above; both are cited rather than silently resolving the inconsistency)
AlShanableh Z, Woodall A, Chisdak M, et al. Plasma Sodium Correction Rates in Patients with Severe Hyponatremia Treated with Hypertonic Saline with and without Proactive Desmopressin. Kidney360. 2025;6(9):1462-1471. (Desmopressin dosing observed in practice ~1.6-2 mcg every 6-8 hours; this paper's own study defined "overcorrection" as >8 mEq/L/24h as its research methodology, which is not the same as a guideline ceiling for every 24h window — see the note below)
Phekoo A, Sparks MA. Use of the Desmopressin Clamp in Hyponatremia: Smooth Sailing or Turbulent Waters? Kidney360. 2025;6(9):1430-1432. (Editorial reviewing proactive vs. reactive/rescue desmopressin use; rescue strategy is desmopressin plus a hypotonic fluid such as D5W after overcorrection has already occurred, aiming to relower plasma sodium back below the correction limit; also reviews recent evidence — Seethapathy et al., Ayus et al. meta-analysis — questioning whether the ODS risk from rapid correction alone is overstated relative to other risk factors)
Wang X, Chen X, Zhang L. Correction of extreme hypernatremia in acute kidney injury. Kidney Int Rep. 2017;2:1232-1236, as cited in: Alrashidi FS. Severe Hypernatremia During Continuous Hemofiltration in an End-Stage Renal Disease Patient: A Case Report and Updated Review. Cureus. 2025. (Hypernatremia correction generally should not exceed 10–12 mmol/L per 24 hours — independently confirmed by the StatPearls Hypernatremia chapter above)
Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581-1589. (Origin of the infusate formula used in the 3% Saline Infusion tab: predicted rise per liter of infusate = [Infusate Na − Serum Na] / [Total Body Water + 1]. This paper is paywalled and was not read directly — the formula and the 513 mEq/L value for 3% NaCl were independently confirmed by recomputing a worked example from the open-access case report below, which matched almost exactly)
Kawasaki RJ, et al. Refractory SIAD Triggered by Herpes Zoster Ophthalmicus: Impact of Postherpetic Neuralgia on Hyponatremia Duration and the Role of Tolvaptan. Intern Med. 2025 (online ahead of print). (Open-access worked example: 57.1 kg man, serum Na 116 mEq/L, predicted ~11.2 mEq/L rise per liter of 3% saline via the Adrogue-Madias formula — matches this tool's independent recalculation of 11.26 mEq/L. Also documents a predicted 2.24 mEq/L rise from a 200 mL bolus that produced only a 1 mEq/L actual rise due to increased urinary sodium loss — the basis for this tool's "recheck frequently" warning)
Dutta DK, Joshi A, Sharma M. Safety of Rapid Intermittent Bolus versus Slow Continuous Infusion of Hypertonic Saline for Managing Symptomatic Severe Hyponatremia: A Systematic Review and Meta-analysis. Ann Afr Med. 2025;24(2):431-437. Open access. (3 studies, 290 patients — both bolus and continuous infusion of 3% saline found safe and effective for severe symptomatic hyponatremia, with no significant difference in overcorrection risk; continuous infusion showed a nonsignificant trend toward shorter hospital stay. Source of the bolus-vs-infusion equivalence claim in the Bolus Protocol card above)
Spasovski G. Hyponatraemia-treatment standard 2024. Nephrol Dial Transplant. 2024;39(10):1583-1592. (Same lead author as the 2014 European Clinical Practice Guideline referenced below — this is the most current single-author treatment standard identified for hyponatremia, published 2024 with an erratum as recently as 2026, suggesting active ongoing revision. Paywalled [Oxford Academic] with no free full text found in this environment; not read directly. Its existence is disclosed here so that institutions with access can check it against the StatPearls/Endotext-sourced ceilings this tool currently uses)
Palmer BF, Clegg DJ. Hyperkalemia treatment standard. Nephrol Dial Transplant. 2024;39(7):1097-1104. (Current nephrology consensus for the Hyperkalemia Management tab: severity tiers 5.5-5.9/6.0-6.4/≥6.5 mEq/L; ECG is unreliable and must not be used to defer treatment at K⁺ >6.0 mEq/L; treatment sequencing of calcium → insulin/dextrose → albuterol → bicarbonate only if acidotic → binders → dialysis)
LaRue HA, Peksa GD, Shah SC. A Comparison of Insulin Doses for the Treatment of Hyperkalemia in Patients with Renal Insufficiency. Pharmacotherapy. 2017;37(12):1516-1522. PMID 28976587. (5-unit vs. 10-unit regular insulin: equivalent K⁺ reduction, significantly less hypoglycemia with 5 units — basis for the insulin dose shown in the Hyperkalemia tab)
FDA prescribing information: Calcium Gluconate Injection (DailyMed); Calcium Chloride Injection 10% (accessdata 021117s025, 2023 — specifies slow infusion via central/deep vein only, not peripheral bolus); Veltassa (patiromer, accessdata 205739Orig1s038, 2023); Lokelma (sodium zirconium cyclosilicate, accessdata 207078s000). (Source of the calcium route caution, and the potassium-binder onset-of-action figures — both binder labels explicitly state they are not for emergency treatment of life-threatening hyperkalemia)
FDA Drug Safety Communication, 2009 (Kayexalate/sodium polystyrene sulfonate label, accessdata 011287s023): serious WARNINGS AND PRECAUTIONS (section 5.1) for intestinal/colonic necrosis, risk heightened with concurrent sorbitol — note the current SPS label carries no boxed warning, so this should not be cited as one. (Basis for the tool's caution against SPS for acute hyperkalemia management)
KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024. kdigo.org. (Corroborates the severity tiers and treatment sequencing above via its own potassium-management content; primarily framed around chronic/RAAS-inhibitor-associated hyperkalemia rather than acute emergency sequencing)
FDA prescribing information: Potassium Chloride for Injection Concentrate (Pfizer/accessdata.fda.gov). (Source of the KCl rate ceiling in the K/Mg/Phosphate/Ca tab — ≤10 mEq/hr routine, up to 40 mEq/hr with continuous cardiac monitoring for severe/urgent hypokalemia, 24-hour max 200 mEq; the label itself does not distinguish peripheral from central administration — that split is disclosed in-app as institutional/nursing-reference convention, not an ISMP-numbered standard, since a current ISMP document with those exact peripheral/central figures could not be located)
FDA prescribing information: Magnesium Sulfate Injection USP 50% (Hospira), DailyMed, rev. Aug 2021. (Dilute to ≤20% before IV use; max IV push rate ≤150 mg/min; 1-2 g/hour noted in the label as a common continuous-infusion practice rather than a stated hard ceiling)
FDA prescribing information: Calcium Gluconate Injection, DailyMed, rev. Nov 2023. (Bolus dilution 10-50 mg/mL, continuous-infusion dilution 5.8-10 mg/mL, max rate 200 mg/min adult / 100 mg/min pediatric/neonatal — used for both the routine hypocalcemia repletion dose in this tab and cross-referenced from the Hyperkalemia tab's calcium gluconate rec)
ISMP List of High-Alert Medications in Acute Care Settings, January 2024. ismp.org. (Confirms KCl, IV magnesium, and IV phosphate salts as ISMP-designated high-alert medications; does not itself publish the specific peripheral/central mEq-per-100-mL numbers commonly taught — disclosed as a gap rather than misattributed)
Bello A, et al. Diagnosis and Treatment of Hyponatremia: Compilation of the Guidelines. Open access, PMC5407738. (Cross-source compilation of the 2013 US expert panel [Verbalis et al.] and 2014 European Clinical Practice Guideline [Spasovski et al.] — source of the Urine Na <30 mEq/L cutoff for identifying hypo-/hypervolemic hyponatremia, and the fluid-restriction thresholds [<1 L/day general, <500 mL/day if urine:serum electrolyte ratio >1] used in the Hyponatremia Diagnostic Workup tab)
"Hyponatremia" and "Syndrome of Inappropriate Antidiuretic Hormone Secretion." StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. NBK470386, NBK507777. (SIADH diagnostic criteria and cause list, primary polydipsia/low-solute-intake/hypothyroidism/secondary adrenal insufficiency differentiation)
FDA prescribing information: SAMSCA (tolvaptan), DailyMed. (Boxed warning: hospital-only initiation/reinitiation with close Na monitoring; do not use for more than 30 days; avoid in underlying liver disease including cirrhosis — basis for the tolvaptan cautions in the Hyponatremia Diagnostic Workup tab)
Verbalis JG, Goldsmith SR, Greenberg A, et al. Diagnosis, Evaluation, and Treatment of Hyponatremia: Expert Panel Recommendations. Am J Med. 2013;126(10 Suppl 1):S1-42. Paywalled, not read directly in this environment — cited via the Bello et al. compilation above and secondary summaries; independent verification recommended if your institution has access.
Spasovski G, Vanholder R, Allolio B, et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant. 2014;29(Suppl 2):i1-i39. Paywalled, not read directly in this environment — same disclosure as above.
"Hypernatremia." StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. NBK441960. (Urine osmolality-based diagnostic framework, central/nephrogenic DI causes, hypotonic fluid loss and sodium-gain etiologies used in the Hypernatremia Diagnostic Workup tab)
Desmopressin Nasal Spray, Summary of Product Characteristics. UK Electronic Medicines Compendium (EMC). (DDAVP challenge test protocol — timing of fluid restriction and urine osmolality measurements — and FDA prescribing information for the 10-40 mcg/day central DI treatment dose)
Akkara S, et al. Redefining Diagnostic Cut-Offs for the Indirect Water Deprivation Test. Clin Endocrinol. 2024. Open access, PMC11694560. (Proposed a refined ≥54% urine osmolality rise threshold for central DI in a small cohort — basis for this tool's disclosure that the classic >50%/<15% cutoffs vary across sources rather than being a single fixed number)
Fenske W, et al. A Copeptin-Based Approach in the Diagnosis of Diabetes Insipidus. N Engl J Med. 2018;379:428-439. Winzeler B, et al. Arginine-stimulated copeptin measurements in the differential diagnosis of diabetes insipidus. Lancet. 2019;394(10198):587-595. (Basis for this tool's note that copeptin-based testing is displacing the classic water-deprivation/desmopressin test as the reference standard where available; identified via search, not independently read in full text this session)
Disclosure (Hyperkalemia Management tab): the severity tiers, calcium/insulin/albuterol/bicarbonate sequencing, and binder onset-of-action figures above are sourced directly to Palmer & Clegg 2024 and current FDA labels (see reference list). One specific detail — whether to withhold the dextrose bolus and give insulin alone when baseline glucose is ≥250 mg/dL — came from secondary clinical-guide sources during development, not an independently confirmed primary source; the tool discloses this inline when that branch is shown and defers to institutional protocol. The 10-20 mg albuterol dose range is well-corroborated, but exact onset/peak-effect timing was intentionally left out of this tool's output rather than stated with false precision.
Disclosure (Hyponatremia & Hypernatremia Diagnostic Workup tabs): the two 2013/2014 primary hyponatremia guidelines (Verbalis et al., Spasovski et al.) are paywalled and were not read directly in this environment — the urine Na/osmolality cutoffs and fluid-restriction thresholds in the Hyponatremia Diagnostic Workup tab instead rest on a cross-source compilation review (Bello et al., PMC5407738) plus StatPearls, both freely accessible and cross-checked against each other. The exact SIADH urine-sodium cutoff (cited here as >30 mEq/L) varies between >30 and >40 mEq/L across secondary sources — disclosed in-app rather than presented as a single precise number. For the Hypernatremia Diagnostic Workup tab, the classic DDAVP-challenge cutoffs (>50% central DI, <15% nephrogenic DI) are long-standing teaching but a 2024 study proposed a different threshold in a small cohort, and copeptin-based testing is emerging as a more accurate alternative reference standard — both disclosed in-app. Neither workup tab is a substitute for endocrinology/nephrology consultation, especially for ambiguous/partial results.
Disclosure & revision note (K/Mg/Phosphate/Ca tab — pharmacist-workflow pass): a new Calcium section and concentration/rate-limit advisories were added for KCl, MgSO₄, potassium phosphate, and calcium gluconate — the specific IV verification checks (max peripheral/central concentration, max infusion rate) a hospital pharmacist actually checks against, which this tab previously lacked. An initial research pass assumed these peripheral-vs-central concentration splits would be found in a specific ISMP guidance document; direct verification found no such current, freely-accessible ISMP document with these exact numbers, so the split is now correctly attributed to common institutional/nursing-reference practice layered on top of the (less conservative, route-agnostic) FDA label ceilings, rather than misattributed to ISMP — see the reference list for the FDA labels this section is sourced to directly.
Revision note (bolus protocol, most recent audit): the 3% Saline tab previously offered only a continuous-infusion (Adrogué-Madias) calculator, with the guideline-preferred bolus approach for severe symptomatic hyponatremia mentioned only as a passive text note. Because guidelines specifically favor 100 mL boluses over a calculated infusion for severe symptoms (seizures, obtundation, delirium) — and a 2025 meta-analysis independently confirmed both approaches are similarly safe — the bolus protocol was promoted to its own interactive calculator, placed first in the tab, with the continuous-infusion calculator now explicitly scoped to mild-to-moderate symptoms or ongoing correction.
Revision note (two-tier ceiling, earlier audit): an earlier version of the Hyponatremia tab used a single flat 8 mEq/L/24h ceiling for every 24-hour window, sourced only to the "overcorrection" definition used in the AlShanableh et al. 2025 study's own methodology. Cross-checking against the StatPearls and Endotext chapters above (both current, freely accessible, and independent of each other) found this was too strict for the first 24 hours specifically — the actual guideline-anchored ceiling for the first 24h is 10 mEq/L (European CPG), with a 6-8 mEq/L pragmatic target, and the 8 mEq/L ceiling applies to every 24h period after the first. The tool now reflects this two-tier structure. The two core hyponatremia expert guidelines themselves (Verbalis JG et al., Am J Med. 2013;126(10 Suppl 1):S1-42; Spasovski G et al., Nephrol Dial Transplant. 2014;29(Suppl 2):i1-i39) remain paywalled and could not be accessed in full text in this environment — the StatPearls and Endotext chapters are themselves secondary sources that summarize those guidelines, not the guidelines directly. If your institution has access to either original guideline (or the 2024 update above), independent verification against the full text is still worthwhile.
Clinical Disclaimer: ElectrolyteRx is a reference and verification aid for licensed healthcare professionals. It is not autonomous clinical software and does not replace clinical judgment, patient-specific assessment, institutional protocol, or — for sodium correction specifically — frequent laboratory monitoring and nephrology/endocrinology input for severe or symptomatic derangements.
Tool information, sources & feedback
Clinical review: A complete, dated review of this tool is not recorded here. An interface update does not certify its clinical content.
Population & limitations: Read the selected module’s eligibility, exclusions, and warnings alongside its result. Coverage differs by module; a result alone does not establish eligibility.
Distinguish FDA labeling, guideline-supported practice, original validation studies, and institutional protocols when applying a recommendation. Source dates and limitations belong to each recommendation; no site-wide “verified” status is implied.
Report a clinical or interface problem · Interface release: site-2026-09-06. Reports include tool and release identifiers only; no patient inputs or results are attached.