Hyperkalemia is defined as a serum or plasma potassium level above the upper limits of normal, usually greater than 5.0 mEq/L to 5.5 mEq/L. While mild hyperkalemia is usually asymptomatic, high levels of potassium may cause life-threatening cardiac arrhythmias, muscle weakness or paralysis. Symptoms usually develop at levels higher levels, 6.5 mEq/L to 7 mEq/L, but the rate of change is more important than the numerical value. Patients with chronic hyperkalemia may be asymptomatic at increased levels, while patients with dramatic, acute potassium shifts may develop severe symptoms at lower ones. Infants have higher baseline levels than children and adults. Pseudohyperkalemia is quite common and represents a false elevation in measured potassium due to specimen collection, handling, or other causes. Hyperkalemia should always be confirmed before aggressive treatment in cases where the serum potassium is elevated without explanation. True hyperkalemia may be caused by increased potassium intake, transcellular movement of intracellular potassium into the extracellular space, and decreased renal excretion. The urgency of therapy depends on symptoms, serum levels and explanation for hyperkalemia.
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