Lab Notes

Telomere Length Test

To learn about the telomere length test, please go here

What are telomeres?

by Patricia Shelton, MD

A telomere is a cap on the end of a chromosome.  The discovery of telomeres was so important to science and medicine that the 2009 Nobel Prize was awarded to three scientists who made the initial discoveries in the field1.  To understand why telomeres are critical, it helps to have a little background in genetics.


What does a telomere test measure?

by Patricia Shelton, MD

The telomere test is a blood test.  While most of your blood cells don’t contain DNA, your white blood cells, or leukocytes, do contain DNA.  These are the cells that are used to measure your telomere length1.  The measurement you receive is called your leukocyte telomere length, or LTL.  The LTL is an average of the length of the telomeres in the cells from your blood sample; it’s been shown in studies to be highly correlated with the length of telomeres measured in other tissues of the body2.


How can I protect my telomeres from shortening?

by Patricia Shelton, MD

Having learned that the shortening of telomeres is thought to be a major contributor to aging, you’re likely to be wondering how you can keep your telomeres as long as possible.  And while there are some factors associated with telomere length that you can’t control, such as your gender1, how long your parents lived2, and how difficult your childhood was3, there are quite a few things you can do to help keep your telomeres long and healthy.


What factors affect telomere length?

by Patricia Shelton, MD

It’s been said that telomere length “captures the interplay between genetics, life experiences, and psychosocial and behavioral factors”1.  In other words, your telomere length can be affected by nearly everything in your life.


How is Telomere length measured?

Measurement of telomere length is done on white blood cells, or leukocytes.  These cells are used because they’re the only blood cells that contain DNA.  Isolation of the DNA from these cells allows the measurement of leukocyte telomere length, or LTL.  Studies have shown that LTL is correlated with telomere length in other body tissues1, making the measurement of LTL a reliable method of determining overall average telomere length.


In order to measure LTL, the leukocytes are first collected, usually from the blood.  This may involve venipuncture (collection of blood from a vein through a needle) or a fingertip prick, from which blood is collected in a small tube or a blood spot collected on special paper2.  In some tests, a cheek swab is used3.