Signs and symptoms include muscle weakness, paralysis, hypothermia, and cardiac abnormalities (irregular conduction and arrhythmias).
ECG changes of hyperkalemia do not reliably correlate with potassium levels, but mild elevation (5.5-6.5 mmol/L) may cause peaked T waves, shortened QT interval, and ST-segment depression.
At higher levels of potassium (< 8.0 mmol/L), the ECG may demonstrate peaked T waves, PR prolongation with decreased P waves, and widening QRS. At potassium levels > 8.0 mmol/L, P waves may be absent, with progressively widening QRS, and intravesicular / fascicular / bundle branch block development, progressing to a sine wave pattern, followed by ventricular fibrillation or asystole. It is important to note that approximately 50% of patients do not have ECG changes even with serum potassium > 6.0 mmol/L, however. Still, the absolute level of serum potassium is important in predicting morbidity and mortality, along with the rate at which it is reached and how long the patient remains hyperkalemic.
Pseudohyperkalemia can be caused by improper blood drawing techniques, hemolysis, tourniquet use, and clenched fists.
In addition to acquired hyperkalemia, hyperkalemic periodic paralysis is an autosomal dominant inherited disorder that causes fluctuating potassium levels and episodic muscle weakness when potassium levels are high.
E87.5 – Hyperkalemia
14140009 – Hyperkalemia
Increased potassium release from cells
- Pseudohyperkalemia – serum potassium is 0.5 mmol/L > plasma potassium
- Metabolic acidosis
- Hypertonicity / hyperglycemia
- Beta blockers
- Hyperkalemic periodic paralysis
- Tissue injury (eg, rhabdomyolysis, trauma / surgery, tumor lysis)
- Excess consumption of potassium-rich foods (banana, potatoes, melons, citrus, avocados)
- Salt substitutes (common in patients with CKD)
- Oliguric renal failure
- Acute or chronic kidney disease
- Hyporeninemic hypoaldosteronism
- Type 4 renal tubular acidosis
- Drugs – angiotensin inhibitors, NSAIDs, calcineurin inhibitors (cyclosporine, tacrolimus), heparin, potassium-sparing diuretics
- Mineralocorticoid deficiency or resistance
- Cortical collecting tubule defect