What condition is characterized by a peaked T-wave on an electrocardiogram (ECG)?

Peaked T-wave on Electrocardiogram: Characteristic of Hyperkalemia

Peaked T-wave on electrocardiogram is a characteristic feature of hyperkalemia (c), not hypernatremia, hypermagnesemia, hypocalcemia, or hyponatremia.

ECG Changes in Hyperkalemia

Hyperkalemia produces a progressive sequence of ECG changes that correlate with increasing serum potassium levels:

• 5.5-6.5 mmol/L: Peaked/tented T waves (earliest and most common sign) 1
• 6.5-7.5 mmol/L: Prolonged PR interval, flattened P waves 1
• 7.0-8.0 mmol/L: Widened QRS complex, deep S waves 1
• >10 mmol/L: Sinusoidal pattern, ventricular fibrillation, asystole, or pulseless electrical activity 1

Identifying Peaked T Waves

Peaked T waves in hyperkalemia have specific characteristics:

• Narrow-based, symmetrical, and pointed appearance
• Most commonly visible in precordial leads (V2-V4)
• T wave amplitude often exceeds normal limits
• May be accompanied by QT interval shortening

Clinical Significance

The presence of peaked T waves on ECG is critically important for several reasons:

• Serves as an early warning sign of potentially life-threatening hyperkalemia
• May be the only initial indication of hyperkalemia before laboratory confirmation
• Indicates need for urgent intervention to prevent cardiac arrhythmias
• Helps monitor response to treatment

Diagnostic Considerations

While peaked T waves are characteristic of hyperkalemia, several important caveats should be noted:

1. The sensitivity of ECG changes for detecting hyperkalemia is variable. Some studies show that T wave alterations poorly predict serum potassium levels in certain populations, particularly those with acute kidney injury 2.

2. Other conditions that may cause peaked T waves include:

   • Early myocardial ischemia
   • Left ventricular hypertrophy
   • Cerebrovascular accidents
   • Normal variant in young adults

3. Multiple electrolyte disturbances occurring simultaneously may generate ECG abnormalities that are not as readily recognizable 3.

Management Implications

When peaked T waves are identified on ECG:

1. Obtain immediate serum potassium measurement
2. Implement cardiac monitoring
3. Consider immediate treatment if clinical suspicion is high:
   • Calcium gluconate 10% (20 mg/kg IV) for cardiac membrane stabilization 1
   • Insulin with glucose for intracellular potassium shifting 1
   • Additional therapies based on severity and clinical context

Conclusion

Peaked T waves represent an important early ECG manifestation of hyperkalemia that should prompt immediate clinical attention. While other electrolyte abnormalities can cause ECG changes, the characteristic narrow-based, symmetrical peaked T wave is most consistently associated with elevated serum potassium levels.