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What is hyperkalaemia?

Hyperkalaemia is the medical term for higher than normal potassium levels in the blood. (It should not be confused with hypokalaemia, which is the medical term for lower than normal potassium levels).

Potassium is a key mineral in the human body.  We get potassium from the food we eat (including meat, vegetables, fruit and milk) and almost all of it is stored in our cells. However, the levels of potassium in the bloodstream are very important. Potassium levels control the electrical impulses in nerves and muscles. Minor changes in the potassium level in the blood can affect muscle contraction and heart rhythms. Extreme changes can cause the heart to stop, sometimes with very little warning.

Causes of hyperkalaemia

Our kidneys are responsible for keeping blood potassium levels normal (known as ‘regulating’), no matter how much potassium we have in our diets. But kidney disease can reduce their ability to regulate potassium levels, particularly when kidney function drops below around 20%. This means that having a diet high in potassium can cause dangerous hyperkalaemia for people with advanced chronic kidney disease.

If you have kidney disease, other factors can also help to raise potassium levels:

  • Taking certain drugs, for example:
    • Tablets often prescribed to control blood pressure or for heart failure e.g., ACE inhibitors, angiotensin receptor blockers, and some diuretics (such as spironolactone, epleronone, triamterene and amiloride)
    • Non-steroidal anti-inflammatory drugs e.g., Diclofenac, Ibuprofen and Naproxen
    • Some beta-blockers
    • Digoxin (a drug often prescribed for heart issues)
  • Becoming dehydrated, for instance due to diarrhoea or vomiting
  • Having blood transfusions
  • Developing acidosis (Where reduced kidney function results in the kidneys being unable to excrete acids into the urine and causes the blood to become acidic)

Hyperkalaemia symptoms

Hyperkalaemia can alter the function of your nerves and muscles and can cause:

  • muscle weakness
  • a slow heart beat, and, in severe hyperkalaemia, the heart stopping altogether.

The danger with hyperkalaemia is that it often causes very few symptoms, even in patients at high risk of the heart stopping.

Hyperkalaemia diagnosis

Your kidney doctors will do regular blood tests to check your potassium levels. The most common group of tests is known as ‘U&Es’, which stands for ‘urea and electrolytes’ (potassium is an ‘electrolyte’). Hyperkalaemia would be suspected if your blood test showed high levels of potassium. In blood test reports, potassium levels are listed as ‘K’, which is the chemical symbol for potassium.

However, sometimes the way your blood is taken or handled may lead to a falsely high potassium concentration, so a second test may be required.

  • Don’t panic if you get an ‘abnormal’ test result; but don’t ignore it either. Speak to your kidney doctor or nurse if you are concerned and always go to A&E if you’re told to do so – even if you feel perfectly fine.

Hyperkalaemia treatment

Treatments for hyperkalaemia will differ, depending on the severity of the condition.

If you have severe hyperkalaemia you will usually be admitted to hospital as an in-patient and given treatments including:

  •  Nebulised salbutamol via a face mask or T piece tube in your nostrils (this is a treatment usually given for asthma, but it helps to push down the potassium level as well)
  • Intravenous glucose and insulin (this also helps to push down the potassium level)
  • Dialysis (to remove potassium from the body)

If your hyperkalaemia is less severe your treatments may include:

  • Changing the drugs you take to ensure you avoid taking any that could raise your potassium level
  • Taking additional drugs such as diuretics to increase your production of urine, potassium binders to prevent absorption of potassium through the gut and sodium bicarbonate to regulate blood acid levels
  • Changing your diet to control the intake of foods and drinks containing potassium. But you should only restrict your diet if advised to do so by a kidney healthcare professional.

Help for you

Don’t hesitate to speak to your kidney specialist or dialysis unit if you have any concerns about hyperkalaemia – or if you need help with any other aspects of your illness.

Reviewed April 2019

Fiona Karet

Professor Fiona Karet

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