Also Known As
K
Formal Name
Potassium
This article was last reviewed on
This article waslast modified on 1 April 2019.
At a Glance
Why Get Tested?

To determine if the concentration of potassium in your blood is within normal range.

When To Get Tested?

Blood potassium concentrations are frequently measured as part of routine health screening and in the clinical investigation of many diseases. It is measured in those who take diuretics or heart medications, and in the investigation of high blood pressure and kidney disease. It is also used to monitor patients on kidney dialysis or diuretic therapy, and patients receiving intravenous therapy on a drip

Sample Required?

A blood sample taken from a vein in the arm

Test Preparation Needed?

None

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, gender, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

Potassium is present in all body fluids, but most potassium is within your cells. Only a very small amount of potassium is contained within the serum or plasma component of the blood. In health, the amount of potassium within serum is tightly controlled, however, many illnesses / drugs can cause concentrations of potassium to become too high or too low. An abnormal concentration can alter the function of the nerves and muscles including those of the heart.I In extreme cases you may experience disturbances to your heart beat or the heart muscle may even lose its ability to contract.

How is the sample collected for testing?

A blood sample is taken by needle from a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

Accordion Title
Common Questions
  • How is it used?

    The test is performed to identifyconcentrations of potassium that are too high (hyperkalaemia) or too low (hypokalaemia). Potassium is typically measured along with sodium and creatinine as part of a “renal function test”. The test may be conducted as part of routine health screening or for monitoring of patients with conditions that are known to cause abnormalities in potassium . The test is also used to monitor patients taking drugs that can effect potassium excretion.

    Once your doctor discovers the reason for the abnormal potassium concentration in the blood, it can be treated.

  • When is it requested?

    Blood potassium concentrations are frequently measured as part of routine health screening and in the clinical investigation of many diseases. It is measured in those who take diuretics or heart medications, and in the investigation of high blood pressure and kidney disease. It is also used to monitor patients on kidney dialysis or diuretic therapy, and patients receiving intravenous therapy on a drip.

  • What does the test result mean?

    A raised blood potassium concentration is called hyperkalaemia. Kidney disease is a common cause of hyperkalaemia. In this condition the body is less able to excrete potassium in the urine and so the levels within the blood rise. Some drugs also decrease the kidney’s ability to excrete potassium potentially leading to hyperkalaemia. Among them are non-steroidal anti-inflammatory drugs (such as ibuprofen) and drugs used to treat high blood pressure such as angiotensin-converting enzyme (ACE) inhibitors (such as captopril), and potassium-sparing diuretics (such as spironolactone). There are many other conditions that can cause hyperkalaemia, including diabetes and addison’s disease. In hospitalised patients, hyperkalaemia may occur if the patient is given too much potassium in a drip.

    A low blood potassium concentration is called hypokalaemia. Hypokalaemia can occur due to excessive loss of potassium for example due to severe diarrhoea and vomiting. Potassium can also be lost through your kidneys in urine. In rare cases, potassium may be low because you are not getting enough in your diet. If you have diabetes, your potassium concentration may fall after you take insulin, particularly if your blood glucose concentrations have been too high for a while. Low potassium is commonly due to 'water pills' (diuretics); if you are taking these, your doctor will check your potassium level regularly.

  • Is there anything else I should know?

    The way that your blood is taken and handled can affect the potassium concentration in your blood sample. If you clench or pump your fist a lot while your blood is being collected the potassium concentration in the blood may rise. If blood cells are damaged during sample collection they can burst and release potassium into the blood, giving a falsely raised potassium result. Some tubes that are used to collect blood sample into contain potassium salts as a preservative. If your blood sample is collected into one of these tubes by mistake, the potassium concentration in the sample will be falsely high.

    Potassium can also be elevated if the specimen takes a long time to travel from your GP surgery (or where you had the blood test) to the laboratory.

    If there are any questions as to how your blood was collected, your doctor may request that the test be repeated before starting any treatment.

  • What are appropriate treatments for the common causes of low potassium (hypokalaemia) and high potassium (hyperkalaemia)?

    Treatment for hypokalaemia may include the use of potassium supplements such as Sando K and increasing the amount of potassium-rich foods in the diet, such as bananas, beef, or spinach. Treatment for hyperkalaemia is usually based on treatment of the underlying cause and may include the use of diuretics, kidney dialysis, or insulin injections.

  • What are some good dietary sources of potassium?

    A number of fruits, vegetables, and meats are good sources of potassium. Examples are bananas, melons, orange juice, potatoes, spinach, broccoli, milk, yoghurt, turkey and beef.

  • Is there an over-the-counter test I can use to check my potassium levels?

    No. Electrolyte tests are performed by trained, highly skilled, healthcare scientists using highly sensitive instruments in accredited laboratories.

  • Would a sports drink help with my electrolyte levels?

    Sports drinks offer a quick replacement of electrolytes, but your body can replenish them naturally using its own storage supply of minerals.