Definition
• See Adult Metabolic Abnormalities for etiologies
History
• Hyponatremia: Fatigue, weakness, lethargy, agitation, szs; ask re: renal dz or GI distress
• Hypernatremia: Irritability, lethargy, szs, fever, over or lack of urination
• Hypokalemia: Weakness, smooth muscle Dysfxn, lethargy, confusion, decreased GI motility, respiratory insufficiency, rhabdomyolysis, polyuria
• Hyperkalemia: Asymptomatic to generalized weakness, paralysis, paresthesias
• Hypocalcemia: Tetany, weakness, fatigue, paresthesias, laryngospasm, sz, irritability
• Hypercalcemia: Weakness, respiratory distress, apnea, HA, sz, abdominal pain, lethargy, anorexia, constipation, bone pain, signs of kidney stones, pancreatitis, N/V, psychosis
• Hypomagnesemia: Anorexia, nausea, weakness, nonspecific psychiatric sxs
• Hypermagnesemia: Lethargy, confusion, respiratory distress
Physical Exam
• Hyponatremia: May appear euvolemic, dehydrated or hypervolemic; severe hyponatremia = lethargy, hyporeflexia, Cheyne–Stokes respiration
• Hypernatremia: Poor skin turgor, increased muscle tone, altered sensorium; severe hypernatremia = spasticity, lethargy, hyperreflexia, respiratory paralysis
• Hypokalemia: Skeletal muscle weakness, hyporeflexia, lethargy, confusion
• Hyperkalemia: Paralysis, hyporeflexia, confusion
• Hypocalcemia: Tetany, wheezing/inspiratory stridor, Chvostek/Trousseau
• Hypercalcemia: Respiratory distress, apnea, hyporeflexia, epigastric tenderness, elevated BP
• Hypomagnesemia: Anorexia, nausea, weakness, clonus, tetany, Chvostek/Trousseau
• Hypermagnesemia: Lethargy, hyporeflexia, hypotension, respiratory failure
Evaluation
• Labs: R/o spurious lab draws, hemolysis (hyperkalemia); CBC, Chem 7, Ca/Mg/phosphorus, urine electrolytes; ABG if acidotic & respiratory decline, UA, lipase
• ECG: U wave (hypokalemia), peaked T/widened QRS/ventricular tachycardia (hyperkalemia), prolonged QT (hypocalcemia), shortened QT (hypercalcemia), ventricular arrhythmia/torsades de pointe (hypomagnesemia)
Treatment
• Supportive: Continuous cardiac monitoring, O2 sat monitoring, 2 large-bore IVs
• Electrolyte monitoring: Chem 7, Ca, Mg, phosphorus q4h
• Electrolyte correction:
• Hyponatremia: See Adult Metabolic section; determine volume status; children should not be corrected >10 mEq/L/d in hypovolemia; acute onset <48 h hyponatremia can be corrected more quickly over 24 h; 3% NS at 6 mL/kg infusion over 1–2 h for severe neuro sx; consider loop diuretics; tx underlying cause
• Hypernatremia: See Adult Metabolic section for Na correction (start w/ NS & complete w/ ½NS w/ goal Na reduction rate of 0.5–1 mEq/L/h); consider vasopressin/DDAVP for DI
• Hypokalemia: Correct alkalosis, hypomagnesemia
• IV: 0.5–1 mEq/kg IV (max 40 mEq/dose) w/ infusion rate not to exceed 0.3–0.5 mEq/kg/h; in life-threatening situations, infuse at ≥0.5 mEq/kg/h (require ECG monitoring)
• PO: 2–4 mEq/kg/d PO in divided doses
• Hyperkalemia:
• Calcium gluconate: 50–100 mg/kg/dose IV, up to adult dose
• Calcium chloride (code situation): 10–25 mg/kg/dose IV, up to adult dose over 2–5 min
• Glucose + insulin: 1 g/kg IV of D25W + 0.25 U/kg IV insulin
• Sodium bicarbonate: 1–2 mEq/kg/dose IV over 5–10 min
• Albuterol 2.5–5 mg nebulized
• Furosemide 1–2 mg/kg IV/PO; hydrochlorothiazide 1 mg/kg PO up to 200 mg
• Kayexalate: 1–2 g/kg PO
• Dialysis
• Hypocalcemia: Send ionized calcium
• Symptomatic:
• Calcium gluconate 10%: 50–100 mg/kg IV slowly over 5–10 min to control szs; IV infusion at 50–75 mg/kg/d over 24 h; use calcium chloride (dose as in hyperkalemia) in code situation
• Asymptomatic:
• Calcium carbonate: Neonates: 30–150 mg/kg/d PO divided QID; children: 20–65 mg/kg/d PO divided BID/QID
• Hypercalcemia: Send ionized calcium
• NS: (Weight-based bolus + 1.5 times maintenance); furosemide
• Bisphosphonates: Etidronate 7.5 mg/kg/d IV over 2 h OR pamidronate 1–1.5 mg/kg IV QD
• Calcitonin: 3–6 mcg/kg IV q6h
• Dialysis: In extreme hypercalcemia & renal failure
• Hypomagnesemia:
• PO: Magnesium gluconate 10–20 mg/kg TID/QID
• IV: Magnesium sulfate 25–50 mg/kg IV over 2–4 h
• Hypermagnesemia:
• NS:
• <10 kg: 100 mL/kg/d
• 10–20 kg: 50 mL/kg/d
• >20 kg: 20 mL/kg/d
• Furosemide: 1 mg/kg/dose q6–12h; titrate to effect
• Calcium gluconate/calcium chloride (same dose as hyperkalemia)
• Dialysis: Severe renal failure, cardiac or neuromuscular Dysfxn
Disposition
• Home: Mild, asymptomatic electrolyte abnormalities may be discharged home w/ PCP f/u in 1–2 d for repeat labs
• Admit: All pts w/ symptomatic electrolyte abnormalities should be admitted & monitored; consider ICU level care for HD unstable or those w/ severe cardiac or neurologic disturbances