Potassium blood test in Chiswick

What the test measures

Potassium is an electrolyte, a mineral that carries an electrical charge. Most of it sits inside cells, and the balance between potassium inside and outside cells is what allows nerves to send signals, muscles to contract and the heart to keep a regular rhythm. Even small changes in the blood level can matter.

The kidneys are responsible for keeping potassium steady, removing any excess in urine. Hormones such as aldosterone, and many common medicines, influence how much is kept or lost. Potassium is therefore usually read alongside sodium, urea, creatinine and eGFR, as part of what is often called a U&E (urea and electrolytes) check.

Your price includes the sample taken at our Chiswick clinic, analysis at the Randox accredited laboratory, a practitioner review of your result and a GP feedback report on request. No GP referral is needed.

Who it is for

• You take blood pressure tablets such as ACE inhibitors, or diuretics, and need a routine check.
• You have reduced kidney function, diabetes or high blood pressure.
• You have had a spell of vomiting or diarrhoea and want to check your electrolytes have recovered.
• You have muscle weakness or cramps and your practitioner wants to look at your minerals.
• You take potassium supplements or salt substitutes and want to confirm your level.

Understanding your result

A low potassium is often linked to diuretics, vomiting, diarrhoea, laxative use or, less often, hormone conditions. A raised potassium can be caused by reduced kidney function, some blood pressure medicines, potassium supplements or salt substitutes. Raised results are also very often false: if red blood cells are damaged during sampling, or if the sample is delayed, potassium leaks out of the cells and the reading appears higher than it really is. A raised result is usually repeated before any conclusion is drawn.

Your report shows the laboratory reference range. A result outside it is a prompt for discussion with your practitioner, not a diagnosis. If a result is markedly abnormal, we will advise you on prompt medical follow-up.

Preparing for your test

No fasting is needed. Drink water normally and keep taking your usual medicines unless your doctor has told you otherwise. Try to keep your arm relaxed and avoid clenching your fist repeatedly during the blood draw, as this can falsely raise potassium. Tell us about any diuretics, blood pressure tablets, supplements or salt substitutes you use.

Potassium is part of the Kidney Health Check, which reads it alongside sodium, urea, creatinine and eGFR, and of Omnia Essential Plus. You can compare every blood test and price in Chiswick.

Questions

How much is a potassium blood test in Chiswick?

A potassium test costs £49. This includes your sample at our clinic, laboratory analysis, a practitioner review and a GP feedback report on request.

Why might my potassium be falsely high?

Potassium can leak from red blood cells if they are damaged during the draw or if the sample is delayed. This is common, which is why a raised result is often repeated.

Which medicines affect potassium?

Diuretics can lower it, while ACE inhibitors, some other blood pressure tablets and potassium-sparing diuretics can raise it. Your practitioner will take your medicines into account.

Should I book this test if I feel very unwell?

No. If you have palpitations, severe muscle weakness or feel faint, seek urgent medical care by calling 111 or 999 rather than booking a routine test.