1 Emergency Assessment of Severe Electrolyte Disorders

Prioritize stabilization

Severe electrolyte abnormalities can cause seizures, altered consciousness, respiratory failure, and fatal arrhythmias. In an unstable patient, prioritize airway, breathing, and circulation; use cardiac monitoring when indicated and begin immediate treatment of the suspected cause.

Obtain a 12-lead ECG and urgent laboratory tests, but do not delay emergency stabilization while waiting for confirmatory results. The treatment principles here concern adult assessment; use local protocols and expert consultation for patient-specific care.

Manage severe sodium disorders

Severe hyponatremia

Severe hyponatremia with a seizure or other serious neurologic symptoms is an emergency. Give monitored boluses of 3% hypertonic saline. The initial goal is a modest sodium rise of about $4\text{–}6\,\mathrm{mmol/L}$ to reduce cerebral edema and improve symptoms, not to normalize sodium immediately.

Check sodium frequently and prevent overcorrection, which can cause osmotic demyelination. Use a stricter correction limit for patients at high risk. For example, a patient with sodium $111\,\mathrm{mmol/L}$ who becomes confused and has a generalized seizure needs monitored hypertonic saline rather than fluid restriction, oral salt alone, or rapid normalization.

Respond to potassium disorders

Hyperkalemia

Hyperkalemia with ECG changes indicates cardiotoxicity. Give IV calcium promptly to stabilize the cardiac membrane; calcium does not remove potassium or lower serum potassium. Then use potassium-shifting therapy, commonly insulin with glucose and glucose monitoring, and/or an inhaled beta-agonist. Arrange definitive potassium removal; dialysis may be required, especially with kidney failure or persistent severe hyperkalemia.

Peaked T waves may be followed by PR prolongation and QRS widening, although ECG findings vary. A patient with kidney failure, potassium $7.0\,\mathrm{mmol/L}$, peaked T waves, and a widening QRS requires prompt stabilization and treatment rather than waiting for a repeat result or starting with an oral potassium binder.

Hypokalemia

Hypokalemia can cause weakness, flattened T waves, ST depression, prominent U waves, and dangerous arrhythmias. Replace potassium with controlled, monitored dosing according to local protocol; never give a routine IV potassium bolus. Check renal function and magnesium, because low magnesium can make hypokalemia difficult to correct and increase arrhythmia risk.

For example, a patient with prolonged vomiting, potassium $2.4\,\mathrm{mmol/L}$, weakness, flattened T waves, and prominent U waves needs monitored replacement and assessment of magnesium and renal function.

Respond to calcium disorders

Hypocalcemia

Stridor, tetany, and QT prolongation in suspected acute hypocalcemia are emergency findings. Give IV calcium gluconate with ECG monitoring for severe symptomatic hypocalcemia, and check magnesium because deficiency can contribute to hypocalcemia and make it refractory to treatment.

A patient who develops tingling around the mouth, carpopedal spasm, and stridor several hours after thyroid surgery, with QT prolongation, needs urgent IV calcium rather than oral calcium alone or treatment directed at hypokalemia.

Hypercalcemia

Severe hypercalcemia can cause dehydration, neurologic impairment, kidney injury, and dysrhythmia; a shortened QT interval is a recognized ECG finding. Assess volume status and renal and cardiac function. IV isotonic saline is commonly used to restore volume when appropriate, but its rate and amount must be individualized, particularly in heart or kidney failure.

Arrange treatment directed at the cause. Additional treatment, such as an antiresorptive drug, depends on the cause and specialist assessment. A patient with cancer, dehydration, confusion, markedly elevated calcium, and a shortened QT needs urgent assessment and volume management when appropriate, not routine fluid restriction or treatment of the ECG finding alone.

Manage magnesium emergencies

Hypomagnesemia and torsades de pointes

Torsades de pointes is a life-threatening ventricular arrhythmia with polymorphic complexes that twist around the baseline. It is associated with prolonged QT and may be promoted by hypomagnesemia or hypokalemia. Give IV magnesium and follow emergency rhythm-management protocols; if the patient is unstable or pulseless, provide immediate resuscitation and defibrillation as indicated. Review QT-prolonging medicines and correct contributing electrolyte abnormalities.

Hypermagnesemia

Severe hypermagnesemia can depress reflexes, blood pressure, heart rate, breathing, and cardiac conduction. Stop magnesium sources, support airway and circulation, and give IV calcium to temporarily counteract magnesium’s effects. Diuresis may be considered when kidney function and volume status permit; severe toxicity with renal impairment may require hemodialysis.

For example, advanced kidney disease and magnesium-containing laxatives may precede hypotension, lethargy, bradycardia, respiratory depression, and diminished reflexes. These signs call for stopping magnesium exposure and supporting the patient, not giving additional magnesium.

Interpret ECG findings and prioritize

Use ECG patterns as clues

• Peaked T waves followed by PR prolongation and QRS widening are associated with hyperkalemia, although ECG findings vary.

• Flattened T waves and prominent U waves may occur with hypokalemia.

• Prolonged QT is associated with hypocalcemia; shortened QT can occur with severe hypercalcemia.

ECG patterns support assessment but cannot replace clinical evaluation or laboratory testing.

Prioritize simultaneous cases

A patient with sodium $119\,\mathrm{mmol/L}$ and a seizure needs immediate seizure and airway care, followed by monitored hypertonic saline. At the same time, a patient with potassium $6.8\,\mathrm{mmol/L}$, no symptoms, and a normal initial ECG still needs cardiac monitoring, prompt potassium confirmation, and assessment for urgent treatment based on risk and results.

A normal ECG does not reliably exclude dangerous hyperkalemia. Confirm potassium promptly, but do not let confirmation delay treatment if instability or ECG changes develop. Prioritize according to the immediate clinical risks rather than assuming that one electrolyte disorder is always more urgent than another.