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Serum potassium

Potassium is an electrolyte found in body fluids and inside cells. An imbalance of potassium in the blood can be dangerous and affect the nerves and muscles, including the heart. Among other things, potassium measurements provide information about kidney function and the cause of certain heart rhythm disorders.

What is the purpose of this test? This test is frequently performed as part of a regular check-up. It is used to monitor and diagnose potassium imbalances that can occur in the following populations:
  • People taking certain medications
  • People with kidney or adrenal gland damage
  • People receiving parenteral nutrition
  • People experiencing symptoms due to too little or too much potassium in the blood
How to prepare?
  • No preparation is required for this test.
Reference values*
  • 3.5-5.0 mmol/L
Associated tests
  • Potassium levels are often measured alongside other electrolytes such as sodium, calcium, chloride, magnesium, and phosphate. It can be measured at the same time during a full electrolyte panel performed on a single blood sample.
  • Potassium is also often evaluated alongside creatinine.
How is it done? Small blood sample, usually taken from a vein in the arm.
How long before I get the results? Results are usually ready in a day. It may take longer to receive your results.
* These values are presented for information purposes only. As different laboratories may have different target values, the lab report usually specifies the values used for the test. It should also be noted that test results must be interpreted based on factors such as age, sex, and health condition. Values outside of this range may be considered normal for some individuals.

What does an abnormal test result mean?

High values of potassium (hyperkalemia):

High potassium levels may be caused by one or more of the following factors:

  • Old age
  • Diabetes
  • Heart failure
  • Renal impairment

Low values of potassium (hypokalemia):

Low potassium levels can be caused by the following:

Decreased absorption caused by:

  • Poor diet or malnutrition
  • Malabsorption
  • An eating disorder (anorexia)

Increased excretion caused by:

  • Severe and repeated vomiting
  • Diarrhea
  • Laxative abuse
  • Intestinal fistulas
  • Hyperaldosteronism
  • Cushing's syndrome

Medications that may affect test results

Several medications can influence test results. Here are a few examples:

High potassium values (hyperkalemia):

  • Non-steroidal anti-inflammatory drugs (e.g., ibuprofen, celecoxib)
  • Certain classes of medication for high blood pressure and heart problems
  • Potassium supplements

Low potassium values (hypokalemia):

  • Certain types of diuretics
  • Certain laxatives
  • Insulin

Factors that can interfere with test accuracy

The following factors may affect potassium test results:

  • Damage to blood cells during sampling, which may release potassium
  • The use of a blood sample tube containing potassium as a preservative
  • Long sample transport times
  • Clenching and releasing of the fist before or during sampling

What you should know before going for this test

When you go in for a blood test or any other medical exam, it's always a good idea to bring a complete list of any prescriptions, over-the-counter medications, or natural health products you're taking. Unless otherwise advised, it's best to take your medications as usual on blood test days. If in doubt, don't hesitate to talk to your healthcare professional.

© Copyright Vigilance Santé

The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.

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