L-Dex Lymphedema Test

Lymphedema is a condition that can case significant swelling of the arm or leg due to extra lymph fluid build-up in that part of the body. This can occur when the lymph system, which normally drains excess fluid, is damaged due to cancer therapies.


The Lymphedema Index (L-Dex) is a measurement system that helps assess unilateral lymphedema of the arm or leg (swelling occurring in only one).

Why should a patient have an L-Dex measurement?

Lymphedema can occur any time following cancer treatment. Most occurs within the first two years following surgery, but it can develop as late as 10 years following cancer treatment. It is important to have regular L-Dex measurements to determine any potential swelling in your arms or legs.

Early detection of lympedema is critical to aid in successful treatment and reversal of the condition. L-Dex measurements are a non-invasive and sensitive method to aid in the assessment and early detection of lymphedema of the limb.

L-Dex measurments taken prior to cancer treatments and at regular intervals subsequent to surgery can help your physician:

  • Establish a baseline for what is "normal" for you
  • Assess the early stages of lymphedema
  • Show you how treatment or management is progressing
  • Give you peace of mind

How is L-Dex measured?

L-Dex measurements are made by passing a harmles electrical signal of very low strength through your body.  Both arms or both legs will be measuring during the process.

How does the L-Dex system work?

The electrical signal travels through the fluid surrounding the cells which make up the muscle and tissues of the limb. The amount of this fluid increases as lymphedema develops. Increased fluid means the electrical signal will travel more easily through the limb.

The L-Dex system compares how easily the electrical signal travels in the unaffected and affected (or at-risk) limbs and generates an L-Dex value from this comparison.

What does an L-Dex value mean?

The L-Dex value indicates the difference in the amount of fluid in the unaffected and affected limbs. L-Dex values are displayed again a normal healthy range.

How does the L-Dex assessment help a patient?

The L-Dex system is best used as a series of measurements over time. This aids the health care professional to:

  • Assess early stages of lymphedema in patients at risk of developing the condition and therefore start therapy as soon as possible
  • Accurately assess the effectivement of therapy for those who already have lymphedema

L-Dex values indicative of lymphedema should decrease as a result of effective therapy.

Preparing for your L-Dex measurement

When going for a reading, be sure that you:

  • Are normally hydrated
  • Have an empty bladder
  • Have not exercised two hours prior to reading
  • Have not consumed caffeine two hours prior to reading
  • Have not consume alcohol 12 hours prior to reading

If stockings or pantyhose are worn, prepare to remove them before the reading is taken.

Notify the clinician if there is a possibility of pregnancy, if you have a pacemaker or other implanted electronic device or any metal implants, such as pins or plates in bones.

The team of experts at Mercy focuses on finding the root cause of medical issues. We use techniques that promote physical, emotional and spiritual well-being. We'll help you identify simple lifestyle changes that can help you live a healthier life to assist with your own healing process.