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Potassium in Whole Blood by Substance Concentration

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

This test measures the amount of potassium, a vital mineral, in your blood. Potassium helps regulate heart rhythm, muscle function, and fluid balance.

Quick summary

["Potassium levels can affect heart health and muscle function—keep them balanced for normal body function."]

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

Key facts at a glance

LOINC
41656-0
Short code
Potassium BldMV-sCnc
Synonyms
Potassium BldMV-sCnc
Category
electrolyte
Sample
whole-blood
Container
Lavender-top (EDTA)
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
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 like low potassium (hypokalemia), high potassium (hyperkalemia), or to monitor kidney function, heart health, or certain medications that affect potassium levels.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves drawing blood from a vein. Wear loose clothing and stay hydrated unless instructed otherwise.

How the Test Is Performed

A healthcare provider will insert a needle into a vein (usually in your arm) to draw a blood sample. You may feel a slight prick, but the procedure is quick and painless. The blood is then sent to a lab for analysis.

What the Results Mean

Results are compared to standard ranges for your age, sex, and overall health. Very low or very high potassium levels can signal underlying health issues, such as kidney problems, heart conditions, or certain medications.

Reference range

Adult: 3.5-5.0 mmol/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Potassium Level (Whole Blood)

Frequently asked questions

What causes potassium levels to change in the blood?
Potassium levels can be affected by diet (e.g., high potassium foods like bananas or supplements), kidney function, certain medications (like diuretics or heart medications), dehydration, or illness. If you’re taking medications or have health conditions, discuss them with your doctor.
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 contact you once they’re ready, so check with them for updates if needed.
Can I eat or drink before the test?
If fasting is required (check with your doctor), avoid food and liquids (except water) for 8–12 hours before drawing blood. If no fasting is needed, you can eat and drink normally, but avoid alcohol and caffeine before the test.
  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