Potassium
A blood test that measures potassium levels to assess electrolyte balance and help detect conditions that can affect heart, kidney, and muscle function.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
What this test measures
This test measures the concentration of potassium in blood serum. Potassium is the body's principal intracellular electrolyte, with roughly 98% stored inside cells (particularly skeletal muscle) and only about 2% circulating in the bloodstream. That small extracellular fraction is what this test captures, and despite its modest proportion, it is critically important.
Potassium enables nerve impulse transmission, muscle contraction, nutrient transport into cells, and waste removal out of cells. The heart is especially sensitive to potassium levels: both elevations and drops outside the normal range increase the risk of dangerous cardiac arrhythmias. The kidneys serve as the primary regulators of potassium balance, adjusting how much is retained or excreted in urine, with the hormone aldosterone playing a key role in that process. This test is ordered to evaluate electrolyte status, monitor kidney function, and investigate symptoms like muscle weakness, cramping, or irregular heartbeat.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals taking medications that can affect potassium levels, such as blood pressure medications, diuretics, or heart medications
- Those with kidney disease or conditions that may impact kidney function, as damaged kidneys may not regulate potassium properly
- People with diabetes, heart conditions, or high blood pressure who need regular monitoring of their electrolyte balance
- Individuals experiencing symptoms that might suggest potassium imbalance, such as muscle weakness, fatigue, or heart rhythm irregularities
- Those undergoing treatment for conditions like adrenal gland disorders or taking medications that can alter electrolyte levels
- People following a restrictive diet or using salt substitutes containing potassium who want to monitor their levels
What to expect
Preparation
No special preparation is typically required for this test. Individuals can eat normally and continue taking their regular medications unless specifically instructed otherwise by their healthcare provider. Some medications may affect potassium levels, so it's important to inform the provider about all medications and supplements being taken.
Sample Type
A simple blood draw from a vein, typically from the inside of the elbow or back of the hand
Collection
During the blood collection, a small needle is inserted into a vein to draw the blood sample. The process typically takes less than 5 minutes and may cause only a slight pinch when the needle is inserted. No doctor visit required - individuals can visit any participating lab location.
Turnaround
Results are typically available within 1-2 business days after the sample reaches the laboratory
Understanding your results
The normal range for serum potassium in adults is approximately 3.5 to 5.2 mEq/L (millimoles per liter). The range is intentionally narrow because even modest deviations can affect heart rhythm and muscle function. Both high potassium (hyperkalemia) and low potassium (hypokalemia) can carry serious health implications and typically warrant investigation to determine the underlying cause. Healthcare providers interpret results alongside kidney function, medications (especially diuretics and ACE inhibitors), and clinical symptoms.
| Population | Reference Range | Notes |
|---|---|---|
| Adults | 3.5-5.2 mEq/L (3.5-5.2 mmol/L) | Normal range for healthy adults, though slight variations may exist between laboratories |
| Infants and Children | Age-dependent, up to 6.5 mEq/L in young infants | Reference ranges vary by age, with higher normal levels in very young children and premature infants |
Reference ranges shown are general guidelines. Your lab report will include the specific reference range used by the laboratory that processed your sample, which is the authoritative range for interpreting your results.
What does a “Low” result mean?
Low levels of potassium can affect these important functions in your body. Over time, low levels of potassium in your body can cause effects such as abnormal heart rhythms, muscle weakness and even paralysis. Low blood potassium typically occurs because of an excessive loss of potassium in your digestive tract. This may be due to frequent vomiting, diarrhea or laxative use. Low potassium may also result from certain medications like diuretics, excessive sweating, or inadequate dietary intake. Low levels of potassium can lead to an irregular heartbeat or other electrical malfunction of the heart. High levels cause decreased heart muscle activity. Individuals with low potassium levels may experience muscle cramps, weakness, fatigue, or digestive issues.
What does a “High” result mean?
Hyperkalemia occurs when potassium levels go above 5.5 mmol/L. A potassium level above 6.5 mmol/L can cause heart problems that require immediate medical attention. But too much potassium in your blood can be dangerous. It can cause serious heart problems. High potassium levels may be associated with kidney problems, certain medications (such as ACE inhibitors or potassium-sparing diuretics), dehydration, or conditions affecting the adrenal glands. Potassium and sodium are important for the heart's electrical signals. Too much potassium can affect these signals and cause heart rhythm problems. Symptoms of elevated potassium may include muscle weakness, nausea, or heart rhythm irregularities, though many individuals with mild elevations may not experience noticeable symptoms.
Privacy & confidentiality
All test orders are authorized and results reviewed by an independent, board-certified physician who is not the patient's personal doctor. Your potassium test results are completely confidential and private. The results are <u>not reported to your doctor</u> unless you choose to share them, and they are <u>not part of your medical records</u> maintained by your healthcare provider. Your test results will not appear on insurance statements or explanations of benefits (EOB) since you pay directly for testing. This confidential testing allows individuals to monitor their potassium levels privately, whether for general wellness monitoring or to track levels while taking medications that may affect potassium. No doctor visit required to order this test - you can visit any participating lab location at your convenience. Your results are securely delivered to your private online account and are never shared with employers, insurance companies, or third parties without your explicit consent.
Frequently asked questions
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Last reviewed: April 2026
CPT Code: 84132
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
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