Also Known As
K
Formal Name
Potassium, blood or urine
This article was last reviewed on
This article waslast modified on March 9, 2018.
At a Glance
Why Get Tested?

To determine whether your potassium level is within normal limits; to help evaluate electrolyte balance; to help determine the cause of and monitor treatment for illnesses associated with abnormal potassium levels in the body

When To Get Tested?

When you have symptoms such as muscle weakness and/or irregular heart beat (cardiac arrhythmia) or when an electrolyte imbalance is suspected; at regular intervals when you are taking a medication and/or have a disease or condition, such as high blood pressure (hypertension) or kidney disease, that can affect your potassium level; as part of a routine medical exam

Sample Required?

A blood sample drawn from a vein in your arm; sometimes a random or 24-hour urine sample

Test Preparation Needed?

None

You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

Potassium Reference Range

The reference ranges1 provided here represent a theoretical guideline that should not be used to interpret your test results. Some variation is likely between these numbers and the reference range reported by the lab that ran your test. Please consult your healthcare provider.

Age Conventional Units2 SI Units3
0-18 years Not available due to wide variability. See child's lab report for reference range.
Adult 3.5-5.1 mEq/L 3.5-5.1 mmol/L

1 from Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. 5th edition, St. Louis: Elsevier Saunders; 2011.

2 Conventional Units are typically used for reporting results in U.S. labs

3 SI Units are used to report lab results outside of the U.S.

What is being tested?

Potassium is an electrolyte that is vital to cell metabolism. It helps transport nutrients into cells and removes waste products out of cells. It is also important in muscle function, helping to transmit messages between nerves and muscles. This test measures the amount of potassium in the blood and/or urine.

Potassium, along with other electrolytes such as sodium, chloride, and bicarbonate (total CO2), helps regulate the amount of fluid in the body and maintains a stable acid-base balance. Potassium is present in all body fluids, but most potassium is found within the cells. Only a small amount is present in fluids outside the cells and in the liquid part of the blood (called serum or plasma).

We get most of the potassium we need from the foods that we eat and most people have an adequate intake of potassium. The body uses what it requires and the kidneys eliminate the rest in the urine. The body tries to keep the blood potassium level within a very narrow range. Levels are mainly controlled by aldosterone, a hormone produced by the adrenal glands in the kidneys.

Because the blood concentration of potassium is so small, minor changes can have significant consequences. If potassium levels are too low or too high, there can be serious health consequences; a person may be at risk for developing shock, respiratory failure, or heart rhythm disturbances. An abnormal potassium level can alter the function of the nerves and muscles; for example, the heart muscle may 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. Potassium can also be measured in a random or 24-hour urine sample.

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?

    A potassium test is used to detect abnormal concentrations of potassium, including high potassium (hyperkalemia) and low potassium (hypokalemia). It is often used as part of an electrolyte panel or basic metabolic panel for a routine physical.

    Potassium is an electrolyte that is vital to cell metabolism. It helps transport nutrients into cells and removes waste products out of cells. It is also important in muscle function, helping to transmit messages between nerves and muscles, and is important to heart function.

    The potassium test may be used to help diagnose and/or monitor kidney disease, the most common cause of high blood potassium. It may also be used to evaluate for abnormal values when someone has diarrhea and vomiting, excessive sweating, or with a variety of symptoms. Blood potassium can be abnormal in many diseases. A healthcare practitioner may order this test, along with other electrolytes, to identify an electrolyte imbalance, if metabolic acidosis is suspected, or if there is high blood pressure or other symptoms of illness present. Potassium in particular may be measured when there are symptoms involving the heart.

    The potassium test may also be used to monitor effects of drugs that can cause the kidneys to lose potassium, particularly diuretics, or drugs that decrease potassium elimination from the body and result in high potassium.

    Urine potassium levels may be tested in people who have abnormal blood potassium levels to help determine the cause, such as dehydration. Urine potassium testing is also used for people with abnormal kidney tests to help the healthcare practitioner determine the cause of kidney disease and to help guide treatment.

  • When is it ordered?

    Potassium levels may be ordered when people undergo a routine medical exam or when they are being evaluated for a serious illness.

    Testing may be done when a person has:

    Potassium testing may be ordered at regular intervals when a healthcare practitioner is diagnosing and evaluating hypertension, diabetic ketoacidosis, and kidney disease and when monitoring a patient receiving dialysis, diuretic therapy, or intravenous fluids.

    Urine potassium testing may be done when blood potassium levels are abnormal.

  • What does the test result mean?

    High potassium levels (hyperkalemia) may be seen in conditions such as:

    • Kidney disease
    • Addison disease
    • Injury to tissue
    • Infection
    • Diabetes
    • Dehydration
    • Consuming too much potassium (for example, fruits are particularly high in potassium, so excessive intake of fruits or juices may contribute to high potassium)
    • In patients on intravenous (IV) fluids, excessive IV potassium
    • Certain drugs can also cause high potassium in a small percent of people; among them are non-steroidal anti-inflammatory drugs (NSAIDs), ACE inhibitors, beta blockers (such as propanolol and atenolol), angiotensin-converting enzyme inhibitors (such as captopril, enalapril, and lisinopril), and potassium-sparing diuretics (such as triamterene, amiloride, and spironolactone).

    Low potassium levels (hypokalemia) may be seen in conditions such as:

    • Diarrhea and vomiting
    • Conn syndrome (hyperaldosteronism)
    • A complication of acetaminophen overdose
    • In diabetes, the potassium level may fall after someone takes insulin, particularly if the person has not managed his or her diabetes well.
    • Low potassium is commonly due to "water pills" (potassium-wasting diuretics); if someone is taking these, their healthcare provider will check their potassium level regularly.
    • Additionally, certain drugs such as corticosteroids, beta-adrenergic agonists such as isoproterenol, alpha-adrenergic antagonists such as clonidine, antibiotics such as gentamicin and carbenicillin, and the antifungal agent amphotericin B can cause loss of potassium.

    Potassium urine concentrations must be evaluated in association with blood levels. The body normally eliminates excess potassium, so the concentration in the urine may be elevated because it is elevated in the blood. It may also be elevated in the urine when the body is losing too much potassium; in this case, the blood level would be normal to low. If blood potassium levels are low due to insufficient intake, then urine concentrations will also be low.

    • Decreased urinary potassium levels may be due to certain drugs such as NSAIDs, beta blockers, and lithium or due to the adrenal glands producing too little of the hormone aldosterone.
    • Increased urinary potassium levels may be due to kidney disease, eating disorders such as anorexia, or muscle damage.
  • Is there anything else I should know?

    Potassium levels can be falsely elevated by a variety of circumstances surrounding specimen collection and specimen processing. For example, if someone is clenching and relaxing his or her fist, the potassium level in the blood may increase. If blood samples are delayed in getting to the lab or if the blood tubes are subjected to vigorous shaking or rough handling in transit, potassium may leak from red blood cells and falsely elevate the potassium in the serum. A healthcare practitioner may question elevated potassium results when the numbers do not fit the clinical condition. If there are any questions as to how the blood was collected, the healthcare practitioner may request that the test be repeated to verify results.

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

    Treatment for low potassium may include the use of potassium chloride supplements and increasing the amount of potassium-rich foods in the diet, such as bananas, beef or spinach. Treatment for high potassium may include the use of diuretics, kidney dialysis, or insulin injections.

  • What are some good dietary sources of potassium?

    Foods high in potassium include a number of fruits and vegetables, such as bananas, cantaloupe, grapefruit, oranges, tomatoes, honeydew melons, squash, and potatoes. Other foods such as legumes, nuts, and seeds are good sources of potassium too.

  • Is there a home test I can use to check my potassium level?

    No. Electrolyte tests are performed by trained personnel using sophisticated instruments.

View Sources

Sources Used in Current Review

Garth, D. (2014 July 9, Updated). Hypokalemia in Emergency Medicine. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/767448-overview. Accessed 8/15/15.

Lerma, E. (2014 March 06, Updated). Potassium. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/2054364-overview. Accessed 8/15/15.

Dugdale, D. (2013 April 14, Updated). Low potassium level. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000479.htm. Accessed 8/15/15.

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Waring WS, Stephen AF, Malkowska AM, Robinson OD. Acute Acetaminophen Overdose Is Associated with Dose-Dependent Hypokalaemia: A Prospective Study of 331 Patients. Basic Clin Pharmacol Toxicol. 2007 Nov 28. Abstract available online through http://www.ncbi.nlm.nih.gov/pubmed. Accessed February 2008.

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