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Potassium (Serum or Plasma) Concentration

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

This test measures the amount of potassium in your blood, an important electrolyte that helps regulate heart rhythm, muscle function, and fluid balance.

Quick summary

["Potassium levels can affect heart health and muscle function; check with your doctor if you have symptoms like weakness or irregular heartbeat."]

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

Key facts at a glance

LOINC
17795-6
Short code
Potassium Hyperal Soln-sCnc
Synonyms
Potassium Hyperal Soln-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 This Test Is Done

Your doctor may order this test to check for conditions affecting potassium balance, such as kidney problems, heart issues, or certain medications that alter potassium levels. It’s also used to monitor treatment for conditions like high blood pressure or heart rhythm disorders.

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’s part of a broader blood panel. Avoid eating or drinking anything except water during this time.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but it won’t cause pain afterward. The blood sample is sent to a lab for analysis.

Possible Results and Interpretation

Results are compared to a standard range, but exact values can vary by lab. High or low potassium levels may signal underlying health concerns, so discuss your results with your doctor.

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 or Plasma Potassium

Frequently asked questions

What causes potassium levels to be checked?
Your doctor may order this test if you have symptoms like muscle cramps, fatigue, irregular heartbeat, or if you’re taking medications that affect potassium levels, such as diuretics or certain heart medications.
How long does it take to get results?
Test results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you with the results once they’re ready.
Can diet affect potassium levels?
Yes, foods high in potassium (like bananas, spinach, or potatoes) can influence results. If you’re on a low-potassium diet, avoid high-potassium foods for 24 hours before testing unless instructed otherwise.
  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