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Potassium (Serum) Mass 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 serum.

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
87454-5
Short code
Potassium Spec-mCnc
Synonyms
Potassium Spec-mCnc
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 doctor may order this test to check for conditions affecting potassium levels, such as kidney problems, heart issues, or certain medications that alter electrolyte balance. It can also help diagnose symptoms like muscle weakness, irregular heartbeat, or unexplained fatigue.

What to Expect Before the Test

No special preparation is needed, but avoid eating or drinking for at least 8–12 hours before the blood draw if instructed. Stay hydrated unless your doctor advises otherwise.

What Happens During the Test?

A healthcare provider will draw blood from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and rarely causes discomfort. The blood sample is then sent to a lab for analysis.

What Are Common Results?

Results are reported as a mass concentration (typically in millimoles per liter, mmol/L). While reference ranges vary by lab, low or high levels may signal underlying health concerns.

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.

Low potassium (hypokalemia) can cause muscle cramps, irregular heartbeat, or fatigue, while high potassium (hyperkalemia) may lead to heart rhythm disturbances or weakness. Both conditions require medical attention and may need adjustments to diet, medications, or treatments like IV fluids.

Short name

Serum Potassium

Frequently asked questions

What causes abnormal potassium levels?
Abnormal potassium levels can result from kidney disease, heart conditions, certain medications (like diuretics or steroids), excessive sweating, vomiting, or diarrhea. Chronic conditions like diabetes or adrenal disorders may also play a role.
How long does it take to get results?
Results are usually available within 1–3 business days, depending on lab processing times. Your doctor will discuss them during your follow-up visit.
Can I adjust my diet before the test?
Yes, if your doctor advises it, avoid high-potassium foods (e.g., bananas, spinach) for 24 hours before testing, but always follow their specific 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