Skip to content

T-wave amplitude (serum/plasma)

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

This test measures the electrical activity represented by the T-wave on an ECG, interpreted through the concentration of certain ions in your blood. It helps assess heart health and potential electrical imbalances.

Quick summary

["Your T-wave voltage can signal risks for heart rhythm issues or electrolyte problems."]

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

Key facts at a glance

LOINC
10148-5
Short code
T wave Amp L-V1
Synonyms
T wave Amp L-V1
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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

What Is Measured?

The T-wave amplitude reflects the voltage (strength of electrical charge) of the repolarization phase of your heart’s electrical cycle. This is indirectly related to the balance of electrolytes like potassium and sodium in your bloodstream, which play a key role in heart function.

Why Is This Test Done?

Doctors may order this test to evaluate for conditions affecting heart rhythm, such as arrhythmias, or to check for electrolyte imbalances that could impact electrical signaling in your heart.

How Is It Performed?

This is not a standalone blood test but is derived from an ECG (electrocardiogram). Blood is drawn for electrolyte analysis, and the T-wave amplitude is calculated based on the ECG results.

What Does It Mean?

Abnormal T-wave amplitudes may indicate low potassium (hypokalemia), high potassium (hyperkalemia), or other heart-related issues. Your results will be compared to standard ranges for your age and health status.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: T-wave amplitude can signal underlying heart conditions, such as electrolyte disturbances or cardiac arrhythmias. High or low values may prompt further testing to assess heart health and guide treatment.

Short name

T-wave Voltage

Frequently asked questions

What causes abnormal T-wave amplitudes?
Abnormal T-wave amplitudes can result from electrolyte imbalances (e.g., low potassium), heart disease, certain medications, or stress-related conditions. Always discuss symptoms with your healthcare provider.
Is this test painful?
No, this test involves a blood draw for electrolyte analysis and an ECG, which may cause slight discomfort but is generally well-tolerated. Most people feel minimal pain.
Can I eat or drink before this test?
For blood tests related to electrolytes, fasting may not be required unless specified by your doctor. Follow your provider’s instructions for preparation.
  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