Potassium test Information | Mount Sinai

Hypokalemia test; Hyperkalemia test; K+

This test measures the amount of potassium in the fluid portion (serum) of the blood. Potassium (K+) helps nerves and muscles communicate. It also helps move nutrients into cells and waste products out of cells.

Potassium levels in the body are mainly controlled by the hormone aldosterone.

Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

How the Test is Performed

A blood sample is needed. Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand.

How to Prepare for the Test

Many medicines can interfere with blood test results.

• Your health care provider will tell you if you need to stop taking any medicines before you have this test.
• DO NOT stop or change your medicines without talking to your provider first.

How the Test will Feel

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

Why the Test is Performed

This test is a regular part of a basic or comprehensive metabolic panel.

You may have this test to diagnose or monitor kidney disease. The most common cause of a high blood potassium level is kidney disease.

Potassium is important to heart function.

• Your provider may order this test if you have signs of high blood pressure or heart problems.
• Small changes in potassium levels can have a big effect on the activity of nerves and muscles, especially the heart.
• Low levels of potassium can lead to an irregular heartbeat or other electrical malfunction of the heart.
• High levels cause decreased heart muscle activity.
• Either situation can lead to life-threatening heart problems.

It may also be done if your provider suspects metabolic acidosis (for example, caused by uncontrolled diabetes) or alkalosis (for example, caused by excess vomiting).

Sometimes, the potassium test may be done in people who are having an attack of paralysis.

Normal Results

The normal range is 3.7 to 5.2 milliequivalents per liter (mEq/L) 3.70 to 5.20 millimoles per liter (millimol/L).

Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

High levels of potassium (hyperkalemia) may be due to:

• Addison disease (rare)
• Blood transfusion
• Certain medicines, including angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and the potassium-sparing diuretics spironolactone, beta adrenergic blockers, amiloride and triamterene
• Crushed tissue injury
• Hyperkalemic periodic paralysis
• Hypoaldosteronism (very rare)
• Kidney insufficiency or failure
• Metabolic or respiratory acidosis
• Red blood cell destruction
• Too much potassium in your diet

Low levels of potassium (hypokalemia) may be due to:

• Acute or chronic diarrhea
• Cushing syndrome (rare)
• Diuretics such as hydrochlorothiazide, furosemide, torsemide, and indapamide
• Hyperaldosteronism
• Hypokalemic periodic paralysis
• Not enough potassium in the diet
• Renal artery stenosis
• Renal tubular acidosis (rare)
• Vomiting

Risks

If it is hard to get the needle into the vein to take the blood sample, injury to the red blood cells may cause potassium to be released. This may cause a falsely high result.

Mount DB. Disorders of potassium balance. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector’s The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 17.

Patney V, Whaley-Connell A. Hypokalemia and hyperkalemia. In: Lerma EV, Sparks MA, Topf JM, eds. Nephrology Secrets. 4th ed. Philadelphia, PA: Elsevier; 2019:chap 74.

Seifter JL. Potassium disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 109.

Last reviewed on: 5/1/2021

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A. D.A.M. Editorial team.

Potassium (K) in Blood Test

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Test Overview

A potassium test checks how much potassium is in the blood. Potassium is both an electrolyte and a mineral. It helps keep the water (the amount of fluid inside and outside the body’s cells) and electrolyte balance of the body. Potassium is also important in how nerves and muscles work.

Potassium levels often change with sodium levels. When sodium levels go up, potassium levels go down, and when sodium levels go down, potassium levels go up. Potassium levels are also affected by a hormone called aldosterone, which is made by the adrenal glands.

Potassium levels can be affected by how the kidneys are working, the blood pH, the amount of potassium you eat, the hormone levels in your body, severe vomiting, and taking certain medicines, such as diuretics and potassium supplements. Certain cancer treatments that destroy cancer cells can also make potassium levels high.

A potassium level that is too high or too low can be serious. Abnormal potassium levels may cause symptoms such as muscle cramps or weakness, nausea, diarrhea, frequent urination, dehydration, low blood pressure, confusion, irritability, paralysis, and changes in heart rhythm.

Other electrolytes, such as sodium, calcium, chloride, magnesium, and phosphate, may be checked in a blood sample at the same time as a blood test for potassium.

Why It Is Done

A blood test to check potassium is done to:

• Check levels in people being treated with medicines such as diuretics and for people having kidney dialysis.
• Check to see whether treatment for too low or too high potassium levels is working.
• Check people with high blood pressure who may have a problem with their kidneys or adrenal glands.
• Check the effects of extra nutrition (total parenteral nutrition [TPN]) on potassium levels.
• Check to see whether certain cancer treatments are causing too many cells to be destroyed (cell lysis). Cell lysis syndrome causes very high levels of some electrolytes, including potassium.

How To Prepare

In general, there’s nothing you have to do before this test, unless your doctor tells you to.

How It Is Done

A health professional uses a needle to take a blood sample, usually from the arm.

Watch

• Learning About Your Blood Test
• Learning About Blood Tests for Children

How It Feels

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.

Risks

There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.

Results

Each lab has a different range for what’s normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn’t in the normal range may still be normal for you.

Many conditions can affect potassium levels. Blood potassium levels also vary with age. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.

High values

• High blood potassium levels may be caused by damage or injury to the kidneys. This prevents the kidneys from removing potassium from the blood normally.
• High blood potassium levels can also be caused by conditions that move potassium from the body’s cells into the blood. These conditions include crushing injuries and heart attack.
• Taking too many potassium supplements can also cause high levels of potassium in the blood.
• Too much acid (pH) in the blood makes potassium levels higher by causing the potassium in the body’s cells to “leak” out of cells and into the blood.
• Some medicines, such as aldosterone antagonists and angiotensin-converting enzyme (ACE) inhibitors, can cause high potassium levels.

Low values

• Low blood potassium levels can be caused by high levels of aldosterone (hyperaldosteronism) made by the adrenal glands.
• Other conditions that can cause low blood potassium levels include severe burns, cystic fibrosis, alcohol use disorder, Cushing’s syndrome, malnutrition, vomiting, diarrhea, and certain kidney diseases, such as Bartter’s syndrome. Bartter’s syndrome is a condition characterized by enlargement of certain kidney cells. It is more common in children and may be linked to an abnormally short stature (dwarfism). The cause of Bartter’s syndrome is not fully known.
• Medicines, such as diuretics, are a common cause of low potassium levels.

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Brief description of the blood test for potassium with a breakdown of the results and the reason for the increased and decreased values ​​of the level of potassium in the human body

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A blood test for potassium is a comprehensive examination method that determines the acid-base balance, evaluates the effectiveness of treatment, and also identifies many diseases

Preparation for the study:

• It is forbidden to smoke immediately before taking blood
• Avoid fatty, fried, spicy foods and alcohol from the diet the day before the examination.
• Do not take drugs, undergo FG or X-ray before the examination

Biomaterial type: venous blood

Synonyms (rus): Serum electrolytes

9002 1 Synonyms (eng): Electrolyte panel

Methods studies: inoselective electrodes

Units: mmol/l

Deadlines: 1 day

Why do you need a blood test for potassium?

Potassium is one of the body’s main electrolytes , which have the ability to conduct electrical charges, in addition, they maintain acidity and water balance in cells. Monitoring the level of potassium in the body is of great importance, as it allows you to identify even minor changes in this mineral compound, in which heart rhythm disturbances or other pathologies occur. Potassium enters the human body with food and then excreted by the kidneys.

A blood test for potassium is ordered by the attending physician or other specialist in the following conditions:

• cardiac arrhythmia;
• edema;
• general weakness;
• nausea;
• loss of consciousness.

With the help of the study of blood serum for electrolytes, diseases of the heart, kidneys, liver and many others are detected. A blood test is taken in the morning on an empty stomach from a vein using a syringe and tourniquet, after which it is examined by the method of ion-selective electrodes.

Explanation of the result of the analysis

Normally, the level of potassium in humans is from 3.5 to 5.1 mmol per liter. A decrease in the concentration of potassium below 3.05 mmol per liter can occur with impaired kidney function (called a decrease in potassium “hypokalemia”). In this case, there is difficulty in breathing, vomiting and nausea, muscle weakness, excretion of feces and urine involuntarily.

A sharp increase in potassium above 7.15 mmol per liter is observed with a strong loss of fluid (this condition is called “hyperkalemia”). In this case, a slowing of the pulse, a drop in pressure, or a violation of sensitivity may appear. Also, deviations from the norm can be with diabetes mellitus, muscle disease, disruption of the cardiovascular system. An abnormal amount of potassium in the blood can be in the presence of toxic substances in the body, for example: oxalates, glycolates or aspirin.

The result of the study may be affected by the use of drugs such as estrogens, acetazolamide, phenylbutazone. Against the background of their intake, potassium may increase, and the result of the examination will not be accurate. The concentration of potassium may decrease while taking bicarbonates, theophylline, furosemide and metazalon.

Serum Potassium

Potassium is a mineral element that is an important part of most cells in the human body. It is the main intracellular ion. Together with sodium, it helps to maintain the necessary acid-base balance and ensures the normal functioning of nerves and muscles.

Russian synonyms

K, potassium ions, potassium in the blood.

English synonyms

Potassium, K, Serum.

Test method

Ion-selective electrodes.

Units

mmol/l (millimoles per litre).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for the examination?

• Do not eat for 12 hours before the test.
• No smoking for 30 minutes prior to examination.

General information about the study

Potassium is a cation that interacts with other electrolytes: sodium, chlorine, bicarbonate; together they regulate the exchange of water in the body, muscle contractions, conduct nerve impulses and maintain acid-base balance. Potassium is excreted by the kidneys under the control of aldosterone produced by the adrenal glands in response to the production of angiotensin II and hyperkalemia.

The electrolyte is found mainly in the cells, only a small part of it is in the extracellular fluid and in the liquid part of the blood (plasma), this proportion is 2% of its total content in the body. The plasma potassium concentration is very low, so any, even small, changes will have pronounced consequences. With a significant increase or decrease in its level, a person’s health is in danger: from the development of shock to the formation of respiratory failure or cardiac arrhythmias. Deviations of this indicator from the norm can disrupt the transmission of impulses in muscle tissue and between neurons, for example, the heart muscle may lose the ability to contract.

What is research used for?

• To detect an increase or decrease in potassium levels – hyper- or hypokalemia – in a routine blood chemistry test.
• To control the level of potassium after the appointment of drugs that can affect it, such as diuretics, the frequent use of which is fraught with hypokalemia.
• To assess the patient’s condition in certain chronic diseases that lead to shifts in the concentration of potassium in the blood, for example, in chronic renal failure.

When is the examination scheduled?

• If you suspect any serious disease associated with a violation of the content of potassium.
• In conjunction with other electrolyte tests for a comprehensive assessment of electrolyte balance, especially when prescribing diuretics, heart medications or pressure problems.
• With arterial hypertension, chronic kidney disease.
• During dialysis sessions, diuretic therapy, any intravenous therapy.
• For symptoms of hyperkalemia: excitability, diarrhea, convulsions, oliguria, cardiac arrhythmia with sharp T-waves and progressive gastric fibrillation.
• For symptoms of hypokalemia: malaise, thirst, polyuria, anorexia, weak filling pulse, low blood pressure, vomiting, decreased reflexes, ECG changes with reduced T waves.

What do the results mean?

Reference values: 3.5 – 5.1 mmol/l.

Increased potassium levels – hyperkalemia – may indicate:

• acute or chronic renal failure (impaired concentration and excretory function of the kidneys),
• Addison’s disease (insufficient production of mineralocorticoids responsible for the hormonal regulation of potassium levels),
• hypoaldosteronism (aldosterone is responsible for removing potassium from the body),
• extensive tissue damage (massive release of potassium from the cell),
• infectious diseases,
• diabetes,
• dehydration (blood thickening occurs),
• a large intake of potassium from food, such as fruits and vegetables (bananas, grapefruits, oranges, tomatoes, melons, potatoes) or juices,
• deficiency of mineralcorticoids (ACTH, cortisone and hydrocortisone),
• hyporenin hypoaldosteronism.

A decrease in the concentration of potassium occurs in such pathological conditions as:

• problems with the gastrointestinal tract (vomiting, diarrhea, overdose of laxatives, fistulas, malabsorption syndrome), leading to loss of fluid rich in electrolytes from the body,
• diabetic ketoacidosis,
• primary and secondary hyperaldosteronism,
• Bartter syndrome,
• osmotic/post-obstructive diuresis,
• Cushing’s syndrome (increased production of glucocorticoids that inhibit potassium reabsorption in the kidneys),
• lack of intake of potassium from food (rare).

Hypokalemia can lead to serious cardiac disorders: ventricular extrasystoles, paroxysmal atrial tachycardia, ventricular tachycardia.

What can influence the result?

• Some drugs increase potassium levels: non-steroidal anti-inflammatory drugs, beta-blockers (propranolol, atenolol), angiotensin-converting enzyme inhibitors (captopril, enalapril, lisinopril), potassium-sparing diuretics (amiloride, triamterene, spironolactone), heparin, histamine, mannitol, lithium.