Hyperkalemia

Hyperkalemia (hyper is high, kalium is the Latin name for potassium) is an elevated blood level (above 5.0 mmol/L) of the electrolyte potassium. Extreme degrees of hyperkalemia are considered a medical emergency due to the risk of potentially fatal arrhythmias. more...

Signs and symptoms

Symptoms are fairly nonspecific, and generally include malaise and muscle weakness; mild breathlessness may indicate metabolic acidosis, one of the settings in which hyperkalemia may occur. Often, however, the problem is detected during screening blood tests for a medical disorder, or it only comes to medical attention after complications have developed, such as cardiac arrhythmia or sudden death.

During the medical history taking, a doctor will dwell on kidney disease and medication use (see below), as these are the main causes. The combination of abdominal pain, hypoglycemia and hyperpigmentation, often in the context of a history of other autoimmune disorders, may be signs of Addison's disease, itself a medical emergency.

Diagnosis

In order to gather enough information for diagnosis, the measurement of potassium needs to be repeated, as the elevation can be due to hemolysis of the material in the first sample. Generally, blood tests for renal function (creatinine, blood urea nitrogen), glucose and occasionally creatine kinase and cortisol will be performed. Calculating the trans-tubular potassium gradient can sometimes help in distinguishing the cause of the hyperkalemia.

Electrocardiography (ECG) is generally done early to identify any influences on the heart. High, tent-shaped T-waves, a small P wave and a wide QRS complex (that becomes sinusoidal) all identify the influence of excess potassium on the heart. This finding alone is an important reason for treatment, as it may forewarn ventricular fibrillation.

Often arterial blood gas measurements and renal ultrasound will be performed.

Differential diagnosis

Causes include:

Ineffective elimination from the body

• Renal failure
• Medication. Medication that can cause hyperkalemia (most are antihypertensives):
  • ACE inhibitors
  • Potassium-sparing diuretics (e.g. amiloride and spironolactone)
  • Angiotensin receptor blockers
  • Succinylcholine (also known as suxamethonium, a paralytic used in anesthesia)
• Metabolic acidosis
• Mineralocorticoid deficiency or resistance (many types)
  • Addison's disease
  • Aldosterone defiency
  • Congenital adrenal hyperplasia
• Liddle syndrome, pseudohypoaldosteronism, other defects of renal tubular K excretion

Excessive release from cells

• Rhabdomyolysis, burns or any cause of rapid tissue necrosis, including tumor lysis syndrome
• Massive blood transfusion or massive hemolysis
• Insulin deficiency

Excessive intake

• Intoxication (potassium-containing dietary supplements or salt replacement)

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