Serum Potassium

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

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

When this test is required

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 the Test Detects

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.See MoreSee Less

Preparation for the Test

None

Sample Requirements

A blood sample taken from a vein in the arm

Additional Notes

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.

Selected Tests