Hyperkalemia

Hyperkalemia is defined as a serum potassium concentration higher than the upper limit of the normal range; the range in infants and children is age-dependent, whereas the range for adults is approximately 3.5-5.5 mEq/L. The upper limit may be considerably higher in young or premature infants, as high as 6.5 mEq/L.[5] Degrees of hyperkalemia are defined as follows[6] : 5.5-6.0 mEq/L – Mild 6.1-7.0 mEq/L – Moderate ≥7.0 mEq/L – Severe levels higher than 7 mEq/L can lead to significant hemodynamic and neurologic consequences. levels exceeding 8.5 mEq/L can cause respiratory paralysis or cardiac arrest and can quickly be fatal. Because of a paucity of distinctive signs and symptoms, hyperkalemia can be difficult to diagnose. Indeed, it is frequently discovered as an incidental laboratory finding. The physician must be quick to consider hyperkalemia in patients who are at risk for this disease process. (See Etiology.) However, any single laboratory study demonstrating hyperkalemia must be repeated to confirm the diagnosis, especially if the patient has no changes on electrocardiography (ECG). Because hyperkalemia can lead to sudden death from cardiac arrhythmias, any suggestion of hyperkalemia requires an immediate ECG to ascertain whether ECG signs of electrolyte imbalance are present (see Workup). Continuous ECG monitoring is essential if hyperkalemia is confirmed. Other testing is directed toward uncovering the condition or conditions that led to the hyperkalemia (see Workup). The aggressiveness of therapy for hyperkalemia is directly related to the rapidity with which the condition has developed, the absolute level of serum potassium, and the evidence of toxicity. The faster the rise of the potassium level, the higher it has reached, and the greater the evidence of cardiotoxicity, the more aggressive therapy should be. In severe cases, treatment focuses on immediate stabilization of the myocardial cell membrane, rapid shifting of potassium to the intracellular space, and total body potassium elimination. In addition, all sources of exogenous potassium should be immediately discontinued. (See Treatment.)