How to correct sodium and potassium imbalances?

How to Correct Sodium and Potassium Imbalances

Sodium Correction

Hyponatremia Management

For severe symptomatic hyponatremia (sodium <125 mEq/L with seizures, altered mental status, or coma), immediately administer 3% hypertonic saline with a target correction of 6 mmol/L over 6 hours or until symptoms resolve, never exceeding 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment

• Classify severity: mild (130-135 mmol/L), moderate (120-125 mmol/L), severe (<120 mmol/L) 1, 2
• Determine volume status through physical examination: look for orthostatic hypotension, dry mucous membranes, decreased skin turgor (hypovolemic); peripheral edema, ascites, jugular venous distention (hypervolemic); or absence of these findings (euvolemic) 1
• Obtain urine sodium and osmolality: urine sodium <30 mmol/L suggests hypovolemia; >20-40 mmol/L with urine osmolality >300 mOsm/kg suggests SIADH 1
• Check serum osmolality, uric acid (<4 mg/dL suggests SIADH), and assess for medications causing hyponatremia 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia:

• Administer isotonic saline (0.9% NaCl) for volume repletion at 15-20 mL/kg/h initially, then 4-14 mL/kg/h based on response 1
• Discontinue diuretics immediately if sodium <125 mmol/L 1
• Maximum correction: 8 mmol/L in 24 hours; for high-risk patients (cirrhosis, alcoholism, malnutrition), limit to 4-6 mmol/L per day 1

Euvolemic Hyponatremia (SIADH):

• Implement fluid restriction to 1 L/day as first-line treatment 1
• If no response, add oral sodium chloride 100 mEq three times daily 1
• For resistant cases, consider vasopressin receptor antagonists (tolvaptan 15 mg once daily, titrate to 30-60 mg) 1

Hypervolemic Hyponatremia (heart failure, cirrhosis):

• Implement fluid restriction to 1-1.5 L/day for sodium <125 mmol/L 1
• In cirrhotic patients, consider albumin infusion alongside fluid restriction 1
• Avoid hypertonic saline unless life-threatening symptoms present, as it worsens ascites and edema 1
• Temporarily discontinue diuretics if sodium <125 mmol/L 1

Critical Correction Rate Guidelines

• Never exceed 8 mmol/L correction in 24 hours to prevent osmotic demyelination syndrome 1
• For severe symptoms: correct 6 mmol/L over first 6 hours, then limit additional correction to 2 mmol/L over remaining 18 hours 1
• High-risk patients (advanced liver disease, alcoholism, malnutrition, prior encephalopathy) require even slower correction: 4-6 mmol/L per day maximum 1
• Monitor sodium every 2 hours during severe symptomatic correction, every 4 hours after symptom resolution 1

Special Considerations for Neurosurgical Patients

• Distinguish cerebral salt wasting (CSW) from SIADH: CSW shows true hypovolemia with CVP <6 cm H₂O, requires volume and sodium replacement (NOT fluid restriction) 1
• For CSW with severe symptoms: administer 3% hypertonic saline plus fludrocortisone 0.1-0.2 mg daily in ICU setting 1
• Never use fluid restriction in subarachnoid hemorrhage patients at risk of vasospasm 1

Management of Overcorrection

• If sodium correction exceeds 8 mmol/L in 24 hours, immediately discontinue current fluids and switch to D5W 1
• Consider administering desmopressin to slow or reverse rapid rise 1
• Watch for osmotic demyelination syndrome signs (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically 2-7 days post-correction 1

Hypernatremia Management

For hypernatremia, use hypotonic fluids (0.45% NaCl or D5W) with maximum correction rate of 10 mmol/L per 24 hours to prevent cerebral edema. 1

• Correct underlying cause: address dehydration, inadequate fluid intake, or excessive water loss 2
• Avoid isotonic saline in hypernatremic patients with renal concentrating defects, as this worsens hypernatremia 1
• For severe hypernatremia or symptomatic patients, use hypotonic fluid replacement with careful monitoring 2

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Potassium Correction

Hypokalemia Management

For moderate hypokalemia (2.5-2.9 mEq/L), administer oral potassium chloride 20-60 mEq/day divided into 2-3 doses, targeting serum potassium 4.0-5.0 mEq/L to prevent cardiac arrhythmias. 3

Severity Classification and Initial Assessment

• Mild: 3.0-3.5 mEq/L (usually asymptomatic, oral replacement sufficient) 3
• Moderate: 2.5-2.9 mEq/L (increased arrhythmia risk, ECG changes possible) 3
• Severe: <2.5 mEq/L (life-threatening, requires IV replacement with cardiac monitoring) 3

Critical first step: Check and correct magnesium levels immediately, as hypomagnesemia is the most common reason for refractory hypokalemia and must be corrected before potassium levels will normalize. 3, 4

Oral Potassium Replacement

• Standard dose: potassium chloride 20-60 mEq/day divided into 2-3 separate doses 3, 5
• Separate doses by at least 3 hours to prevent GI irritation and improve absorption 3
• Take with food or immediately after meals to minimize gastric upset 3
• Target serum potassium: 4.0-5.0 mEq/L (critical for cardiac patients, those on digoxin, or with heart failure) 3

Intravenous Potassium Replacement

Indications for IV replacement:

• Severe hypokalemia (≤2.5 mEq/L) 3
• ECG abnormalities (ST depression, T wave flattening, prominent U waves) 3
• Active cardiac arrhythmias 3
• Severe neuromuscular symptoms (weakness, paralysis) 3
• Non-functioning GI tract 3

IV Administration Protocol:

• Maximum concentration via peripheral line: ≤40 mEq/L 3
• Maximum infusion rate via peripheral line: 10 mEq/hour 3
• For rates >10 mEq/hour or concentrations >40 mEq/L: use central line with continuous cardiac monitoring 3
• Verify adequate urine output (≥0.5 mL/kg/hour) before initiating IV potassium 3
• Recheck potassium levels within 1-2 hours after IV correction 3

Treatment Based on Underlying Cause

Diuretic-Induced Hypokalemia:

• For persistent hypokalemia despite supplementation, add potassium-sparing diuretics (more effective than chronic oral supplements): 3
  • Spironolactone 25-100 mg daily (first-line) 3
  • Amiloride 5-10 mg daily 3
  • Triamterene 50-100 mg daily 3
• Stop or reduce potassium-wasting diuretics if K+ <3.0 mEq/L 3
• Check potassium and creatinine 5-7 days after initiating potassium-sparing diuretic 3

Diabetic Ketoacidosis:

• Add 20-30 mEq potassium per liter of IV fluid once K+ falls below 5.5 mEq/L with adequate urine output 3
• Use 2/3 KCl and 1/3 KPO4 formulation 3
• If K+ <3.3 mEq/L, delay insulin therapy until potassium restored 3

Critical Concurrent Interventions

• Always check and correct magnesium first: Target magnesium >0.6 mmol/L (>1.5 mg/dL) using organic magnesium salts (aspartate, citrate, lactate) 200-400 mg elemental magnesium daily 3, 4
• Correct sodium/water depletion first, as hypoaldosteronism from volume depletion increases renal potassium losses 3
• Stop medications causing potassium wasting: loop diuretics, thiazides, corticosteroids, beta-agonists 3

Monitoring Protocol

• Initial phase: Check potassium and renal function within 2-3 days and again at 7 days after starting supplementation 3
• Stabilization phase: Monitor every 1-2 weeks until values stabilize 3
• Maintenance: Check at 3 months, then every 6 months thereafter 3
• More frequent monitoring required for: renal impairment (eGFR <45 mL/min), heart failure, diabetes, concurrent RAAS inhibitors or aldosterone antagonists 3

Special Populations and Medication Interactions

Patients on ACE Inhibitors/ARBs:

• Routine potassium supplementation may be unnecessary and potentially harmful, as these medications reduce renal potassium losses 3
• If supplementation needed, use lower doses with close monitoring 3
• Avoid combining with potassium-sparing diuretics without specialist consultation 3

Cardiac Patients:

• Maintain potassium strictly 4.0-5.0 mEq/L, as both hypokalemia and hyperkalemia increase mortality 3
• Correct hypokalemia before administering digoxin (hypokalemia increases digoxin toxicity) 3
• Avoid antiarrhythmic agents (except amiodarone, dofetilide) in hypokalemic patients 3

Medications to Avoid During Active Replacement:

• NSAIDs (impair renal potassium excretion, worsen renal function) 3
• Salt substitutes containing potassium (risk of dangerous hyperkalemia) 3
• Digoxin before correction (increased arrhythmia risk) 3

Hyperkalemia Management

For severe hyperkalemia (>6.5 mEq/L) or ECG changes, immediately administer IV calcium gluconate 10-30 mL over 2-5 minutes to stabilize cardiac membranes, followed by insulin-glucose therapy to shift potassium intracellularly. 3

Acute Treatment Protocol

• IV calcium gluconate 10%: 15-30 mL over 2-5 minutes (onset 1-3 minutes, stabilizes cardiac membranes) 3
• Insulin-glucose: Regular insulin 10 units IV with 25g dextrose (onset 30-60 minutes, duration 2-4 hours) 3
• Inhaled albuterol: 10-20 mg nebulized (onset 30-60 minutes) 3
• Recheck potassium within 1-2 hours after treatment 3

Chronic Hyperkalemia Management

• Implement dietary potassium restriction: limit high-potassium foods, avoid salt substitutes 3
• Use newer potassium binders (patiromer or sodium zirconium cyclosilicate) to maintain K+ 4.0-5.0 mEq/L while continuing RAAS inhibitors 3
• Avoid sodium polystyrene sulfonate (Kayexalate) due to severe GI adverse effects including bowel necrosis 3

RAAS Inhibitor Management in Hyperkalemia

• For K+ 4.5-5.0 mEq/L: Initiate or up-titrate RAAS inhibitors with close monitoring 3
• For K+ >5.0-<6.5 mEq/L: Initiate potassium-lowering agent (patiromer or SZC) 3
• For K+ >6.5 mEq/L: Discontinue or reduce RAAS inhibitors immediately, initiate K+-lowering agent 3
• Check potassium 7-10 days after starting or dose-escalating RAAS inhibitors in high-risk patients (CKD, diabetes, heart failure) 3

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Common Pitfalls to Avoid

Sodium:

• Never correct chronic hyponatremia faster than 8 mmol/L in 24 hours—this causes osmotic demyelination syndrome 1
• Don't use fluid restriction in cerebral salt wasting (worsens outcomes) 1
• Don't use hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1
• Don't ignore mild hyponatremia (130-135 mmol/L)—it increases fall risk and mortality 1

Potassium:

• Never supplement potassium without checking and correcting magnesium first—this is the most common reason for treatment failure 3
• Don't combine potassium supplements with potassium-sparing diuretics or ACE inhibitors/ARBs without close monitoring (severe hyperkalemia risk) 3
• Don't administer digoxin before correcting hypokalemia (life-threatening arrhythmias) 3
• Don't use IV potassium bolus in cardiac arrest (unknown benefit, potentially harmful) 3
• Don't exceed 10 mEq/hour via peripheral line without cardiac monitoring 3