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Potassium test
Hypokalemia 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 .
Aldosterone
The aldosterone blood test measures the level of the hormone aldosterone in blood. Aldosterone can also be measured using a urine 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.
Drawn from a vein
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
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 high potassium levels 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).
Metabolic acidosis
Metabolic acidosis is a condition in which there is too much acid in the body fluids.
Alkalosis
Alkalosis is a condition in which the body fluids have excess base (alkali). This is the opposite of excess acid (acidosis).
Sometimes, the potassium test may be done in people who are having an attack of paralysis .
Paralysis
Muscle function loss is when a muscle does not work or move normally. The medical term for complete loss of muscle function is paralysis.
Normal Results
The normal range is 3.7 to 5.2 mEq/L (3.70 to 5.20 millimol/L).
Note: mEq/L = milliequivalents per liter; millimol/L = millimoles per liter.
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:
Hyperkalemia
High potassium level is a problem in which the amount of potassium in the blood is higher than normal. The medical name of this condition is hyperka...
-
Addison disease
(rare)
Addison disease
Addison disease is a disorder that occurs when the adrenal glands do not produce enough hormones.
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- Certain medicines
- Crushed tissue injury
-
Hyperkalemic periodic paralysis
Hyperkalemic periodic paralysis
Hyperkalemic periodic paralysis (hyperPP) is a disorder that causes occasional episodes of muscle weakness and sometimes a higher than normal level o...
ImageRead Article Now Book Mark Article - Hypoaldosteronism (very rare)
-
Kidney failure
Kidney failure
Acute kidney failure is the rapid (less than 2 days) loss of your kidneys' ability to remove waste and help balance fluids and electrolytes in your b...
ImageRead Article Now Book Mark Article -
Metabolic or
respiratory acidosis
Respiratory acidosis
Respiratory acidosis is a condition that occurs when the lungs cannot remove all of the carbon dioxide the body produces. This causes body fluids, e...
ImageRead Article Now Book Mark Article - Red blood cell destruction
- Too much potassium in your diet
Low levels of potassium ( hypokalemia ) may be due to:
Hypokalemia
Low potassium level is a condition in which the amount of potassium in the blood is lower than normal. The medical name of this condition is hypokal...
- Chronic diarrhea
-
Cushing syndrome
(rare)
Cushing syndrome
Cushing syndrome is a disorder that occurs when your body has a high level of the hormone cortisol.
ImageRead Article Now Book Mark Article - Diuretics such as hydrochlorothiazide, furosemide, and indapamide
-
Hyperaldosteronism
Hyperaldosteronism
Hyperaldosteronism is a disorder in which the adrenal gland releases too much of the hormone aldosterone into the blood. Hyperaldosteronism can be pr...
ImageRead Article Now Book Mark Article -
Hypokalemic periodic paralysis
Hypokalemic periodic paralysis
Hypokalemic periodic paralysis (hypoPP) is a disorder that causes occasional episodes of muscle weakness and sometimes a lower than normal level of p...
Read Article Now Book Mark Article - Not enough potassium in the diet
- Renal artery stenosis
-
Renal tubular acidosis
(rare)
Renal tubular acidosis
Proximal renal tubular acidosis is a disease that occurs when the kidneys don't properly remove acids from the blood into the urine. As a result, to...
ImageRead Article Now Book Mark Article - Vomiting
Considerations
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.
References
Seifter JR. Potassium disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 117.
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Blood test - illustration
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.
Blood test
illustration
-
Blood test - illustration
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.
Blood test
illustration
Review Date: 5/3/2015
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
