Home › Biomarkers › Potassium
Potassium is an electrolyte that your cells, nerves, heart and muscles need to work properly. A level that is too low or too high can point to a medical condition, for example of your kidneys.[1]
On this page, you can read what potassium is, what the guidelines say about a level that is too low or too high, what affects your level and which markers are best to look at alongside it.
Also known as: serum potassium, potassium in serum, part of the serum electrolytes. At the lab: K.
Potassium is an electrolyte: a mineral with an electric charge. Electrolytes help control the amount of fluid in your body and the balance between acids and bases (the pH balance). They also help your muscles and nerves do their work.[1]
Almost all the potassium in your body is inside your cells. A small part is in your blood, and that is the part this test measures. Your kidneys remove potassium through your urine. That way, the right amount stays in your blood.[1]
You usually get most of the potassium you need from your food. The test is often part of a standard group of blood tests called an electrolyte panel.[1]
Your cells, nerves, heart and muscles need potassium to work properly. A level that is too high or too low can be a sign of a medical condition and can cause serious health problems.[1]
A doctor may order the test as part of a routine check-up, or to monitor an existing condition, such as a condition of the kidneys or the adrenal glands. You may also need the test if you take medicines that can change your potassium.[1]
With too much potassium, you may have an irregular heart rhythm, tiredness, muscle weakness, nausea, or numbness or tingling. With too little potassium, you may notice an irregular heartbeat, muscle cramps, weak or twitching muscles, tiredness, nausea or constipation.[1]
Labplusarts, the lab BioProfile works with, uses a reference value of 3.5 to 5.0 mmol/l for potassium (K). The lab calls a level between those limits normal.[2]
| Value | What it can mean | Who it is for |
|---|---|---|
| 3.5 to 5.0 mmol/l[2] | The lab calls a value between these limits normal | The lab does not name a separate group |
Source: the reference value of Labplusarts, the lab BioProfile works with. Applies to this lab's potassium test (K).[2]
Having too little potassium in your blood is called hypokalaemia. It can point to side effects of prescription water tablets, fluid loss from diarrhoea, vomiting or heavy sweating, using too many laxatives, or a condition of the adrenal glands or the kidneys. A diet with too little potassium is rarely the cause.[1]
Too much potassium in your blood is called hyperkalaemia and often has two or more causes. It can be a sign that your kidneys are not working properly. It can also point to a condition of the adrenal glands, to wounds, burns or surgery that make your cells release extra potassium, or to side effects of certain medicines, such as water tablets or antibiotics. A diet with too much potassium is rarely the cause.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
Bananas, apricots, leafy green vegetables, avocados and many other foods are good sources of potassium and are part of a healthy diet. Very large amounts of potassium-rich food or potassium supplements can, however, lead to health problems.[1]
Certain prescription medicines, over-the-counter remedies and supplements can raise your potassium. Water tablets can make your level higher or lower. Taking too many laxatives can lower your level.[1]
Natural black liquorice can lower your level. So do not eat any natural black liquorice for at least two weeks before your test. If you eat liquorice, check the label to see which ingredients it contains.[1]
Repeatedly clenching and relaxing your fist just before or during the blood draw can raise your potassium for a short time. That can lead to an incorrect result.[1]
Potassium is in BioProfile 77, 87, 121 and 150.[3]
The BioProfile editorial team wrote this page on 10 October 2026 from the sources below, which we read on 10 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss a value outside the range with your GP.
