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High potassium

Written by Healthwords's team of doctors and pharmacists based in UK | Updated: 10.02.2023 | 3 min read

High potassium, known by doctors as hyperkalaemia, describes when the level of potassium in the blood rises above normal limits. This can cause problems and be life-threatening.

We get our potassium from the food and drink that we consume. Potassium is a substance vital for the function of nerve and muscle cells in your body, including the muscle around your heart. Too much potassium can be very dangerous and very high levels can cause heart attacks or even death.

Normal potassium levels are usually between 3.5 and 5 units. If your potassium level is above 6, it usually requires immediate review and treatment by a doctor.

What causes hyperkalaemia?

Kidney disease is one of the prime culprits in disrupting potassium levels. When your kidneys function normally, one of their jobs is to filter potassium and remove it through your urine. When the kidneys don’t function normally, they are unable to remove enough potassium from your body, causing large amounts to build up in your blood. Kidneys may fail to function in a short-term illness, such as sepsis or gastroenteritis, and this is termed acute kidney injury. Or your kidneys may have been declining over many years, possibly alongside diabetes or high blood pressure, and this is chronic kidney disease. Hyperkalaemia can occur in either condition.

The foods you eat can also give you high potassium. Foods like bananas, orange juice and some sweet fruits have lots of potassium in them. Some medications may also cause the amount of potassium to build up in your body and this should be reviewed by your doctor.

When should I see my doctor?

Most people don’t have any symptoms and it can be found by chance on a routine blood test. If you experience symptoms of high potassium, it is important to contact your doctor immediately as it can be life-threatening. Weakness, muscle fatigue, abnormal heartbeat, nausea and paralysis are common symptoms.

The doctor will want to investigate any underlying cause of your hyperkalaemia. This may involve examination or extra tests. If it is slightly raised and they treat the underlying cause, they may just repeat blood tests to keep an eye on the potassium.

What will my doctor do?

If treatment is required, some medications can be given. Water pills (also called diuretics) help to remove excess potassium through your urine. Potassium binders can also be used, which bind to excess potassium and remove it from the body through your poo.

If the level remains high despite treatment or is at an extremely high level, you may require dialysis, where your blood is filtered by a machine. But this is required very rarely.

Am I fit for work?

If you are unwell and a blood test shows a high level of potassium in your blood, you should take time off to recover from your illness, and your doctor can provide a sick note after the initial seven days.

If a routine blood test shows high potassium, and you are not unwell and have no symptoms, your doctor will advise whether the level is high enough that this needs extra tests or treatment. If so, you should prioritise this over work. If it is mildly raised and you have no symptoms, you may be fit for work, but should prioritise any further blood tests or other investigations, as your doctor recommends.

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