Skip to content

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
2823-3
Short code
Potassium SerPl-sCnc
Synonyms
Potassium SerPl-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?

Doctors may order this test to check for conditions like low potassium (hypokalemia), high potassium (hyperkalemia), or to monitor treatment for kidney disease, heart problems, or other health issues that affect potassium levels.

What Does the Result Mean?

Results are compared to a standard range, but exact values can vary by lab. Abnormal levels may indicate problems with kidney function, heart rhythm, or certain medications.

Common Causes of Abnormal Results

Low potassium can occur from vomiting, diarrhea, excessive sweating, or certain medications. High potassium may result from kidney failure, severe dehydration, or overuse of potassium-sparing diuretics.

When Might You Need Follow-Up?

If your potassium levels are outside the normal range, your doctor may recommend further tests or adjustments to your treatment plan to prevent complications like irregular heartbeats.

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

What triggers a potassium test?
A potassium test may be ordered if you have symptoms like muscle weakness, irregular heartbeat, nausea, or if your doctor suspects conditions like kidney disease, heart problems, or electrolyte imbalances.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time and whether additional tests are needed.
Can diet affect potassium levels?
Yes, foods high in potassium (like bananas, spinach, or nuts) can influence results. If you’re on a low-potassium diet, your doctor may advise temporarily avoiding high-potassium foods before testing.
  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