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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 helps regulate muscle and nerve activity, and imbalances can cause serious health issues."]

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

Key facts at a glance

LOINC
57379-0
Short code
Potassium 2h Ur-sCnc
Synonyms
Potassium 2h Ur-sCnc
Category
electrolyte
Sample
urine
Container
Sterile urine container
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
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
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 low or high potassium levels, which can occur due to conditions like kidney problems, heart disease, or certain medications. It’s also used to monitor treatment progress or diagnose symptoms such as muscle weakness, irregular heartbeat, or fatigue.

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 blood panel. Bring any medications you’re taking to your appointment.

During the Test

A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but it usually takes only a few minutes. The blood sample is sent to a lab for analysis.

What the Results Mean

Results are compared to standard reference ranges for your age and health status. Low potassium (hypokalemia) or high potassium (hyperkalemia) can signal underlying health concerns that need medical attention.

Reference range

Adult: 3.5-5.0 mmol/LN/A

Specimen: urine

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Potassium imbalances can affect heart rhythm, muscle function, and nerve signals. Low potassium may cause weakness, cramps, or irregular heartbeat, while high potassium can lead to dangerous heart complications. Regular monitoring is important for patients with kidney disease, heart conditions, or those taking certain medications (e.g., diuretics, potassium-sparing drugs).

Short name

Potassium Level

Frequently asked questions

What causes low potassium levels?
Low potassium can result from conditions like vomiting, diarrhea, excessive sweating, or kidney problems. Certain medications, such as diuretics, may also deplete potassium. Lifestyle factors like excessive alcohol use or poor diet (low in potassium-rich foods like bananas, spinach, or potatoes) can contribute.
What causes high potassium levels?
High potassium is often linked to kidney failure, severe dehydration, or certain medications (e.g., blood pressure drugs like ACE inhibitors). It can also occur in people with adrenal insufficiency or untreated diabetes. Rapid potassium buildup may be life-threatening and requires immediate medical attention.
How is potassium treated?
Treatment depends on the cause and severity. For low potassium, doctors may prescribe oral supplements or intravenous fluids. For high potassium, treatments like dietary adjustments, medications, or dialysis may be needed to lower levels safely.
  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