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What is potassium?

Potassium is an electrolyte which is essential for cell metabolism. Potassium helps to transport nutrients to cells and removes waste products from cells. Potassium also has an important muscle function as it helps the nerves and muscles to communicate.

Potassium, together with other electrolytes such as sodium, helps to regulate the amount of fluid in the body and maintains a stable acid and alkali balance. Potassium is found in all body fluids, but mostly inside cells. Only a small amount is present in fluids outside the cells.

As the blood concentration of potassium is so small, minor changes to the potassium level can have significant consequences. If potassium levels are too low or too high, there can be serious health consequences; a person may be at risk of developing shock, respiratory failure or heart rhythm disturbances. An abnormal potassium level can alter the function of nerves and muscles; for example, the heart muscle may lose its ability to contract.

Why is it important to analyse potassium?

A potassium test is used to detect abnormal potassium levels, including high potassium (hyperkalaemia) and low potassium (hypokalaemia).

A potassium test can be used to diagnose and/or monitor kidney disease, the most common cause of hyperkalaemia. It can also be used to evaluate abnormal values in patients with diarrhoea and/or vomiting, excessive sweating or a range of other symptoms. Potassium in the blood may be abnormal in many diseases. Potassium in particular can be measured when symptoms are present involving the heart.

A potassium test can also be used to monitor the effects of medications that may cause the kidneys to lose potassium, or medications that reduce the elimination of potassium from the body and result in high potassium levels.

High potassium level

High potassium levels are present with conditions such as:

  • Kidney disease
  • Uncompensated Addison's disease
  • Tissue damage
  • Infection
  • Diabetes
  • Dehydration
  • Consumption of too much potassium (e.g. fruit has particularly high potassium levels, so excessive consumption of fruit or juice may cause high potassium levels)
  • Haematoma resorption and bleeding from the gastrointestinal tract
  • Oliguric renal insufficiency
  • Some medications can also cause high potassium levels

Low potassium levels

Low potassium levels (hypokalaemia) are present with conditions such as:

  • Diarrhoea
  • Vomiting
  • Diabetes – the potassium level may drop after taking insulin
  • Alcoholism
  • Purging
  • Excessive liquorice intake
  • Metabolic alkalosis
  • Diabetic ketoacidosis treated with insulin
  • Cushing's syndrome

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