Hyperkalemia

Definition

Hyperkalemia is the medical term referring to raised blood potassium levels. The normal level of potassium in the blood is in between 3.6 to 5.2 mmol/L. The condition usually produces non specific symptoms like fatigue and generalized body pain. Therefore hyperkalemia is often undiagnosed until it causes complications or it is detected during routine blood tests for another medical condition.

There are number of disease which can lead to elevated serum potassium level, namely kidney diseases, hormonal defects like mineralocorticoid deficiency, excessive burns and blood transfusions. Sometimes the intake of certain drugs like potassium-sparing diuretics and anti-inflammatory drugs (NSAIDs) may lead to elevated serum potassium levels. Hyperkalemia needs immediate medical attention as severe hyperkalemia can cause severe complications and even be fatal.

Symptoms

The symptoms of hyperkalemia are usually non-specific which may include :

  • Fatigue which cannot be explained otherwise.
  • Muscle weakness and pain.
  • Paralysis of limbs
  • Nausea and vomiting.
  • Palpitation, irregular, slow and weak pulse.

Hyperkalemia is a serious life threatening condition, which without treatment, has the potential to progress to arrhythmias even sudden death due to heart block.

Causes

The most commonly found cation inside the cells of the body is potassium. The major functions of potassium include transmission of impulse between nerve cells, maintenance of blood volume and membrane potential of cells. Normal serum potassium is maintained by balance between intake and elimination of potassium from body.

The kidney is the organ responsible for elimination of potassium. Aldosterone, an adrenal hormone, is the principal factor regulating renal excretion of potassium. Whenever there is excessive availability of potassium, either due to increased intake and breakdown of cells or due to decreased elimination because of low level of aldosterone or disease of kidney itself, there is the chance of hyperkalemia developing.

Raised potassium levels usually alter the membrane potential by lengthening the depolarized state which in turn interferes with proper functioning of sodium channels present on the cells. Consequently the function of the nerves, muscles, heart and digestive tract are compromised. The most dangerous outcome occurs due to impairment of conduction in the heart leading to abnormal rhythm and sudden death.

Conditions which may lead to raised serum potassium level are :

  • Kidney disease
  • Intake of certain drugs like :
    – ACE inhibitors used to lower raised blood pressure.
    – Painkillers like NSAIDs.
    – Potassium sparing diuretics like spironolactone and amiloride.
  • Reduced production or resistance to action of aldosterone.
  • Addison’s disease.
  • Renal tubular acidosis type IV, due to resistance to the action of aldosterone.
  • Excessive release of potassium from cells.
  • Rhabdomyolysis.
  • Burns.
  • Massive blood transfusion.
  • Overuse of potassium as dietary supplement such as in a salt substitute.

Sometimes during the drawing of blood for laboratory testing, potassium may leak from the cells showing raised levels without any underlying medical cause. This condition is known as pseudohyperkalemia.

Treatment

Even asymptomatic hyperkalemia should be corrected because of the potential of serious and life threatening complications. The treatment aims at immediate lowering of potassium level by the following measures :

  • Intravenous calcium, glucose or insulin.
  • Dialysis to facilitate potassium elimination.
  • Loop diuretics namely furosemide

Prevention of future attacks should be considered and necessary measures instituted. This is mainly conducted through the following means :

  • Dietary modification (avoidance of potassium rich foods like tomato, potato, oranges, banana).
  • Avoidance of drugs known to raise potassium levels.

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