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Serum or plasma concentration of potassium (measured by ion-selective electrode)

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
7438-5
Short code
Kapok BasoBnd Ab Qn
Synonyms
Kapok BasoBnd Ab Qn
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
lhr
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test to check for conditions affecting your heart, kidneys, or digestive system. It can also help diagnose or monitor symptoms like muscle weakness, irregular heartbeat, or confusion.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel. Bring any medications you’re taking.

How the Test Works

A small blood sample is drawn from a vein in your arm. The sample is sent to a lab where potassium levels are measured using an ion-selective electrode, which detects the mineral’s concentration accurately.

What the Results Mean

Results are compared to a standard range for your age and health. Low potassium (hypokalemia) or high potassium (hyperkalemia) may signal underlying issues like kidney problems, heart conditions, or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Potassium plays a critical role in maintaining normal heart rhythms, muscle function, and nerve signals. Abnormal levels can lead to serious complications, such as irregular heartbeats or muscle weakness, so monitoring is important for patients with chronic conditions like diabetes, kidney disease, or heart failure.

Short name

Potassium (K+)

Frequently asked questions

What causes potassium levels to change?
Potassium levels can rise or fall due to diet (e.g., high potassium foods, diuretics), kidney function, dehydration, or certain medications (like blood pressure drugs). Chronic conditions like kidney disease or heart failure may also affect it.
How long does it take to get results?
Results are typically available within 1–2 business days, depending on your lab’s processing time. Your doctor will discuss them with you during your follow-up visit.
Can I eat or drink before this test?
If fasting is required (e.g., for a metabolic panel), avoid food for 8–12 hours before testing. Water is usually allowed unless specified otherwise. Always follow your doctor’s instructions.
  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