Electrolyte and acid-base emergencies are among the most time-critical problems in acute medicine, and their management is entirely pharmacological. The interventions have precise mechanistic rationales: calcium stabilizes the cardiac membrane without shifting potassium, insulin drives potassium into cells by stimulating Na/K-adenosine triphosphatase (Na/K-ATPase), hypertonic saline raises serum sodium osmotically, and bicarbonate buffers excess protons. Each intervention also carries specific risks — osmotic demyelination from overcorrecting hyponatremia, paradoxical central nervous system (CNS) acidosis from bicarbonate infusion, and rebound hyperkalemia from transient membrane shifts. This module covers the pharmacological management of the four principal electrolyte and acid-base emergencies encountered in clinical practice, and then systematically reviews the drug-induced electrolyte disorders most relevant to trainees and clinicians.
Acute severe hyperkalemia (serum potassium above 6.0 mEq/L with electrocardiogram (ECG) changes, or above 6.5–7.0 mEq/L regardless of ECG) is managed in three mechanistically sequential phases: membrane stabilization, potassium redistribution into cells, and potassium elimination from the body. Understanding that the first two phases do not remove potassium from the body, and that their effects are temporary, is essential for preventing recurrence when the redistribution wears off.1
Calcium gluconate (1 g intravenously over 10 minutes, or calcium chloride 1 g if given via central venous access) is the first-line membrane stabilizer. Calcium raises the threshold potential of cardiac myocytes, increasing the gap between the resting membrane potential and the threshold required to generate an action potential, thereby reducing myocardial excitability and preventing ventricular fibrillation. Calcium does not alter serum potassium or shift potassium into cells; its sole action is cardiac membrane protection. Onset is within 1–3 minutes; duration of action is 30–60 minutes. Calcium chloride contains approximately three times the elemental calcium per gram compared with calcium gluconate but requires central venous access due to its tissue toxicity if extravasated. If ECG changes persist or worsen after the first dose, the dose may be repeated at 5–10 minute intervals. Calcium must be given cautiously in patients on digoxin because hypercalcemia potentiates digoxin toxicity through additive effects on cardiac membrane stability.12
Regular insulin 10 units intravenously, combined with dextrose 50% (50 mL, providing 25 g of glucose), drives potassium into skeletal muscle cells by stimulating Na/K-ATPase activity. This shifts approximately 0.5–1.5 mEq/L of potassium intracellularly over 15–30 minutes. Because this is a transient redistribution effect lasting 4–6 hours rather than elimination, potassium will return to the extracellular space as the insulin effect wanes. Glucose is co-administered to prevent hypoglycemia; monitoring of blood glucose at 1-hour intervals for at least 4 hours after the insulin dose is mandatory. In patients who are already hyperglycemic (blood glucose above 250 mg/dL), glucose co-administration may be deferred, and insulin alone is sufficient to drive the potassium shift.1
Albuterol (salbutamol) nebulization at 10–20 mg (four to eight times the standard bronchodilator dose) activates beta-2 adrenergic receptors on skeletal muscle, stimulating cyclic adenosine monophosphate (cAMP)-mediated activation of Na/K-ATPase and driving potassium into cells. The effect is additive to insulin and lowers potassium by an additional 0.5–1.0 mEq/L over 30–90 minutes. High-dose albuterol causes tachycardia and should be used cautiously in patients with acute coronary syndromes (ACS) or significant arrhythmia burden. Sodium bicarbonate has a limited role in the management of hyperkalemia that is not accompanied by severe metabolic acidosis; in patients with acidemia of pH below 7.1 and concurrent hyperkalemia, bicarbonate administration corrects the pH shift that drove potassium out of cells and is useful, but evidence for its efficacy as a standalone potassium-lowering intervention is weak.1
Potassium elimination from the body is accomplished by renal excretion (if urine output is adequate), gastrointestinal cation exchangers, or dialysis. Loop diuretics increase urinary potassium excretion and are appropriate when renal function is preserved. Patiromer (formerly approved as Veltassa) is a non-absorbed calcium-zirconium polymer that binds potassium in the colon in exchange for calcium, lowering serum potassium over 4–24 hours; its onset is too slow for acute emergencies but it is effective for chronic hyperkalemia management in chronic kidney disease (CKD) patients on renin-angiotensin-aldosterone system (RAAS) blockade. Sodium zirconium cyclosilicate (SZC; brand name Lokelma) is a highly selective potassium-zirconium crystal that traps potassium throughout the gastrointestinal tract via ion exchange; unlike patiromer, SZC has an onset of approximately 1 hour and has regulatory approval for both acute and chronic hyperkalemia management. Hemodialysis provides definitive potassium removal and is indicated in anuric patients, severe refractory hyperkalemia, or cases where membrane stabilization and redistribution fail.1,2
Calcium, insulin, albuterol, and bicarbonate all produce temporary shifts of potassium into cells or membrane stabilization without removing potassium from the body. When these effects wear off (4–6 hours for insulin, sooner for calcium), potassium returns to the serum. Definitive treatment — diuretics, cation exchangers, or dialysis — must always follow the acute stabilization sequence. Failure to establish definitive potassium removal leads to recurrent hyperkalemia after the redistribution phase resolves.
Hyponatremia (serum sodium below 135 mEq/L) is the most common electrolyte abnormality in hospitalized patients and is classified by volume status into hypovolemic (total body sodium depleted), euvolemic (total body water expanded with normal total body sodium, as in SIADH (syndrome of inappropriate antidiuretic hormone secretion), and hypervolemic (both total body sodium and total body water expanded, as in heart failure or cirrhosis). This classification determines treatment: hypovolemic hyponatremia requires isotonic or normal saline to restore sodium and volume; euvolemic hyponatremia (SIADH) requires fluid restriction with or without pharmacological intervention; hypervolemic hyponatremia requires treatment of the underlying cause plus free water restriction, with pharmacological assistance in selected cases. Misclassifying the volume status leads to dangerous treatment errors, most commonly administering saline to a euvolemic SIADH patient, which can paradoxically worsen hyponatremia if the antidiuretic hormone (ADH) effect prevents free water excretion.3
The correction rate for hyponatremia is the dominant safety variable. The current standard limits correction to a maximum of 6–8 mEq/L in the first 24 hours and no more than 10–12 mEq/L in any 24-hour period. Correction faster than these limits, particularly in patients who have had chronic hyponatremia (duration more than 48 hours, where cerebral adaptation has occurred), risks osmotic demyelination syndrome (ODS), a devastating demyelinating injury of the pontine and extrapontine white matter causing dysarthria, dysphagia, spastic quadriparesis, and locked-in syndrome. Patients at highest risk for ODS are those with severe hyponatremia (serum sodium below 115 mEq/L), malnutrition, alcoholism, liver disease, and hypokalemia. Overcorrection must be addressed urgently by stopping the hypertonic saline and, if correction has exceeded target, administering desmopressin (DDAVP) and free water to re-lower the serum sodium toward the safe correction zone.34
Hypertonic saline (3% sodium chloride, containing 513 mEq/L of sodium compared with 154 mEq/L in isotonic saline) is the pharmacological intervention for acute severe hyponatremia with neurological symptoms. The standard approach for symptomatic acute hyponatremia is 100 mL of 3% saline given as an IV bolus, repeated up to twice if symptoms persist, targeting a 5 mEq/L rise in serum sodium sufficient to relieve cerebral edema. For the sustained treatment of chronic hyponatremia requiring correction, 3% saline is infused at 1–2 mL/kg/hour with sodium monitoring every 2–4 hours. The Adrogue-Madias equation provides a starting estimate of the expected sodium change per liter of infusate but is unreliable in real-time and cannot substitute for frequent serum sodium measurements.3
Vasopressin antagonists (vaptans) — tolvaptan (oral, V2-selective) and conivaptan (intravenous, V1a/V2 non-selective) — produce aquaresis (electrolyte-free water excretion) and are pharmacologically suited to SIADH and hypervolemic hyponatremia where total body sodium is not depleted. They are initiated only in monitored inpatient settings and must not be used in hypovolemic hyponatremia. Urea is an underused oral agent for chronic SIADH: it creates an osmotic gradient that promotes water excretion without affecting sodium; doses of 15–30 g/day in water are effective but compliance is limited by palatability. Fluid restriction (typically 800–1000 mL total daily fluid intake) is the cornerstone of SIADH management in stable, non-symptomatic patients and avoids the risks of pharmacological intervention.3,4
Metabolic acidosis is defined by a primary fall in serum bicarbonate (HCO₃⁻) and arterial pH. The approach to bicarbonate therapy depends on the etiology, severity, and clinical context. The anion gap (AG) discriminates between anion gap metabolic acidosis (AG = Na − [Cl + HCO₃] >12 mEq/L, indicating an unmeasured anion such as lactate, beta-hydroxybutyrate, or toxic alcohols) and non-anion gap metabolic acidosis (normal AG, indicating bicarbonate loss from the kidney or gastrointestinal tract, or failure to regenerate bicarbonate, as in renal tubular acidosis (RTA)).5
The established indications for sodium bicarbonate (NaHCO₃) therapy are disorders of renal tubular acidosis (RTA): type 1 (distal) RTA, where the collecting duct fails to secrete hydrogen ions and cannot maintain urine pH below 5.5, and type 2 (proximal) RTA, where the proximal convoluted tubule fails to reabsorb filtered bicarbonate, causing urinary bicarbonate wasting. Type 4 RTA (hyperkalemic, hyporenin-hypoaldosteronism, most commonly from chronic kidney disease (CKD) or calcineurin inhibitor nephrotoxicity) produces mild non-anion gap metabolic acidosis that is treated with sodium bicarbonate if the serum HCO₃⁻ falls below 22 mEq/L. In CKD without overt RTA, metabolic acidosis from reduced net acid excretion is treated with oral sodium bicarbonate when serum HCO₃⁻ is below 22 mEq/L, as acidosis accelerates CKD progression through multiple mechanisms including enhanced complement activation and tubular injury. Severe acute acidemia at pH below 7.1, regardless of etiology, is a relative indication for bicarbonate as a temporary bridge while the underlying cause is addressed.5612
The risks of intravenous bicarbonate infusion are clinically relevant and limit its use in high anion gap metabolic acidosis from lactic acidosis or diabetic ketoacidosis (DKA). Carbon dioxide (CO₂), generated by the buffering reaction (HCO₃⁻ + H⁷ → H₂CO₃ → CO₂ + H₂O), diffuses rapidly across the blood-brain barrier (BBB) while bicarbonate diffuses slowly, transiently worsening cerebrospinal fluid (CSF) acidosis even as blood pH rises — paradoxical central nervous system (CNS) acidosis. Hypernatremia and volume overload result from the sodium load in bicarbonate formulations (1 mEq/mL in standard ampules, 150 mEq/L in isotonic bicarbonate infusions). Overshoot metabolic alkalosis can occur if the underlying acidogenic process resolves while bicarbonate is still being infused. Tromethamine (THAM), an aminoalcohol buffer that accepts protons without generating CO₂, is the CO₂-neutral alternative for patients in whom CO₂ generation or sodium loading are specific contraindications, such as severe combined metabolic and respiratory acidosis; however, THAM use requires intact renal function for its own elimination and can cause hypoglycemia and respiratory depression.5
Type 1 (distal) RTA: collecting duct H⁷ secretion defect → urine pH cannot fall below 5.5 → nephrolithiasis and nephrocalcinosis from calcium phosphate precipitation in alkaline urine. Treat with 1–2 mEq/kg/day oral NaHCO₃. Type 2 (proximal) RTA: PCT HCO₃⁻ reabsorption defect → urinary bicarbonate wasting → requires high doses (5–15 mEq/kg/day) because supplemented bicarbonate is itself wasted. Type 4 RTA: hyperkalemia + mild non-anion gap acidosis; treat the hyperkalemia first as aldosterone deficiency drives both defects. Etiology: diabetic nephropathy, calcineurin inhibitors, NSAIDs, heparin.
Metabolic alkalosis is defined by a primary rise in serum bicarbonate and arterial pH. The urine chloride concentration, measured in an untimed spot urine sample, is the pivotal diagnostic test that separates the two principal etiological categories and determines treatment. Chloride-responsive metabolic alkalosis (urine chloride below 20 mEq/L) indicates chloride and volume depletion as the driving mechanism: loss of hydrochloric acid from vomiting or nasogastric suction, use of loop or thiazide diuretics (which cause chloride and volume loss and secondary hyperaldosteronism), or post-hypercapnia alkalosis. The low urine chloride reflects avid renal chloride conservation in the setting of depletion. Treatment is saline (isotonic sodium chloride) and potassium chloride (KCl) repletion, which corrects the chloride deficit and removes the stimulus for bicarbonate reabsorption; the alkalosis resolves once volume and chloride are restored.7
Chloride-resistant metabolic alkalosis (urine chloride above 20 mEq/L) indicates ongoing aldosterone-mediated sodium reabsorption driving hydrogen ion and potassium secretion in the collecting duct, independent of volume status. Etiologies include primary hyperaldosteronism (Conn syndrome), secondary hyperaldosteronism from renovascular hypertension, Cushing syndrome (excess cortisol activating mineralocorticoid receptors), Bartter and Gitelman syndromes (tubular channel defects mimicking loop and thiazide diuretic use respectively), and licorice ingestion (glycyrrhizin inhibiting 11-beta-hydroxysteroid dehydrogenase, allowing cortisol to activate the mineralocorticoid receptor). Saline will not correct chloride-resistant alkalosis because the aldosterone-driven collecting duct hydrogen and potassium secretion continues regardless of volume repletion; treatment requires addressing the underlying aldosterone excess or channel defect directly.7
Acetazolamide has a specific role in metabolic alkalosis management in volume-overloaded patients (decompensated heart failure, pulmonary hypertension) who cannot receive saline to correct contraction alkalosis. By inhibiting carbonic anhydrase (CA) in the proximal convoluted tubule (PCT), acetazolamide forces urinary bicarbonate wasting, lowering serum bicarbonate toward normal without sodium loading. This is particularly relevant because metabolic alkalosis in these patients impairs loop diuretic efficacy, and correcting the alkalosis with acetazolamide restores diuretic responsiveness. The ADVOR (Acetazolamide in Decompensated Heart Failure with Volume Overload) trial demonstrated that acetazolamide added to intravenous loop diuretics improved decongestion rates in hospitalized heart failure patients, in part through this alkalosis-correcting mechanism. Potassium chloride repletion is essential alongside any treatment for metabolic alkalosis because hypokalemia drives the collecting duct to secrete more hydrogen ion to conserve potassium, perpetuating the alkalosis.78
Amphotericin B, the polyene antifungal used for severe systemic mycoses, inserts into fungal cell membranes at ergosterol-rich domains to form pores that disrupt membrane integrity. At renal tubular concentrations, amphotericin B also forms pores in mammalian tubular cell membranes at cholesterol-rich sites, particularly in the distal tubule and collecting duct. This membrane disruption increases the permeability of the distal tubule to potassium and hydrogen ions, causing potassium wasting and a type 1 (distal) renal tubular acidosis (RTA) pattern. Hypomagnesemia results from reduced magnesium reabsorption in the thick ascending limb (TAL) and distal tubule. Hypokalemia and hypomagnesemia are nearly universal with conventional amphotericin B at cumulative doses and often require aggressive replacement. Lipid formulations of amphotericin B (amphotericin B lipid complex, liposomal amphotericin B) substantially reduce renal tubular toxicity by limiting free drug exposure to tubular cells.9
Cisplatin causes severe and in some cases permanent hypomagnesemia through direct damage to the transient receptor potential melastatin 6 (TRPM6) channel, the primary apical entry channel for magnesium in the distal convoluted tubule (DCT). Cisplatin-induced tubular injury reduces TRPM6 expression and function, impairing magnesium reabsorption and causing urinary magnesium wasting that can persist for months to years after chemotherapy completion even when renal function normalizes. Cisplatin also causes hypokalemia through a similar TRPM6-dependent potassium-magnesium interdependence — hypomagnesemia itself drives renal potassium wasting because magnesium is required to block the renal outer medullary potassium channel (ROMK) from the intracellular side, preventing inappropriate potassium secretion. Hyponatremia from cisplatin occurs through SIADH (syndrome of inappropriate antidiuretic hormone secretion)-like mechanisms in the acute phase and through nephrotoxicity-mediated volume depletion in later cycles. Vigorous pre-hydration with isotonic saline before cisplatin administration reduces but does not eliminate nephrotoxicity and electrolyte losses.910
Lithium, the mainstay of mood stabilization in bipolar disorder, enters collecting duct principal cells via the epithelial sodium channel (ENaC) and accumulates intracellularly, where it inhibits adenylate cyclase-mediated cyclic adenosine monophosphate (cAMP) generation and downstream aquaporin-2 (AQP2) insertion in response to vasopressin (ADH). The clinical result is nephrogenic diabetes insipidus (NDI), which manifests as polyuria (often 3–15 liters/day) and compensatory polydipsia; it affects up to 40% of patients on long-term lithium. Amiloride is the treatment of choice for lithium-induced NDI: it blocks ENaC, reducing lithium uptake into collecting duct cells and thereby attenuating AQP2 downregulation.11 Thiazide diuretics paradoxically reduce lithium-induced polyuria through volume contraction-driven proximal sodium (and lithium) reabsorption, but they increase lithium levels and require close monitoring. Foscarnet, the pyrophosphate antiviral used for cytomegalovirus (CMV) and resistant herpes simplex virus (HSV), chelates ionized calcium and magnesium directly in the tubular lumen, causing symptomatic hypocalcemia (perioral paresthesias, tetany, QT prolongation), hypomagnesemia, and hyperphosphatemia through tubular toxicity.9,11
Tenofovir disoproxil fumarate (TDF), the nucleotide reverse transcriptase inhibitor (NRTI) used in human immunodeficiency virus (HIV) and hepatitis B treatment, accumulates in proximal convoluted tubule (PCT) mitochondria (via tubular secretion by organic anion transporter isoform 1 (OAT1)), where it inhibits mitochondrial deoxyribonucleic acid (DNA) polymerase gamma, causing mitochondrial dysfunction and a full Fanconi syndrome (proximal tubule dysfunction characterized by phosphaturia, glycosuria despite normoglycemia, aminoaciduria, and a type 2 proximal RTA pattern with urinary bicarbonate wasting). TDF also causes direct nephrotoxicity with tubular atrophy. Switching from TDF to tenofovir alafenamide fumarate (TAF), a prodrug that achieves intracellular active metabolite concentrations at 90% lower plasma TDF-equivalent concentrations, substantially reduces renal and bone toxicity while maintaining antiviral efficacy. Calcineurin inhibitors (CNIs) cause hyperkalemia through a type 4 RTA-like pattern: they reduce aldosterone responsiveness in the collecting duct and suppress ENaC activity, impairing potassium secretion; they also downregulate the TRPM6 channel in the DCT, causing hypomagnesemia. Aminoglycosides cause hypomagnesemia and hypokalemia through direct tubular toxicity affecting magnesium reabsorption sites in the TAL and DCT. Proton pump inhibitors (PPIs) cause hypomagnesemia through impairment of intestinal magnesium absorption via the TRPM6 and transient receptor potential melastatin 7 (TRPM7) channels in the small intestinal epithelium, a mechanism distinct from the renal tubular pathology caused by other agents on this list.9,11
Hypokalemia that is refractory to potassium replacement is almost always caused by concurrent hypomagnesemia. Magnesium is required to block ROMK from the intracellular side; without magnesium, ROMK remains constitutively open and potassium is continuously secreted into the collecting duct lumen regardless of how much potassium is given intravenously. Any unexplained persistent hypokalemia, particularly in patients on cisplatin, amphotericin B, aminoglycosides, or CNIs, mandates checking a serum magnesium and replacing it aggressively (IV magnesium sulfate 1–2 g over 30–60 min, repeated) before expecting potassium levels to normalize.
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