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Potassium (Serum or Plasma Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of potassium, a mineral essential for heart function and nerve signaling, in your blood.

Quick summary

["Potassium levels help assess heart health and electrolyte balance."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
12814-0
Short code
Potassium Vitf-sCnc
Synonyms
Potassium Vitf-sCnc
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
3.5
Ref high
5
Critical range
2.5 N/A – 6.5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84132
SNOMED
110742001
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for conditions affecting your heart, kidneys, or acid-base balance. It can also help monitor medications that influence potassium levels, such as certain diuretics or heart medications.

What to Expect Before the Test

No special preparation is needed, but avoid eating or drinking anything (except water) for at least 8–12 hours before the test if instructed. If you’re on potassium-sparing medications, discuss this with your provider.

What Happens During the Test?

A blood sample is drawn from a vein, usually in your arm. The process is quick and typically causes only mild discomfort. The sample is sent to a lab for analysis.

What Are Normal Results?

Results are reported as a concentration in milliequivalents per liter (mEq/L). Normal ranges vary slightly by lab, but values outside the typical range may signal imbalances.

Reference range

Adult: 3.5-5.0 mmol/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Potassium

Frequently asked questions

How long does it take to get results?
Results are usually available within 1–2 business days, depending on lab processing times. Follow-up with your provider to discuss findings.
What causes potassium levels to change?
Potassium levels can be affected by diet (e.g., high potassium foods like bananas or spinach), kidney function, medications (e.g., diuretics, ACE inhibitors), or conditions like heart disease or diabetes.
Can I adjust my diet to affect potassium levels?
While diet can influence potassium levels, sudden changes should be discussed with your provider, especially if you have kidney issues or take medications that affect potassium.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy