ESR Blood Test

What Is the Erythrocyte Sedimentation Rate (ESR) Test and Why Is It Done?

An erythrocyte sedimentation rate (ESR) blood test measures how quickly red blood cells settle to the bottom of a test tube.

Doctors may order an ESR test to:

• look for a sign of inflammation or infection, or to check how well a treatment is working
• see if conditions like inflammatory bowel disease (IBD), arthritis, and lupus are "flaring," or acting up

What Is an Erythrocyte Sedimentation Rate?

An ESR, also called a sedimentation (seh-duh-mun-TAY-shin) rate or sed rate, is how quickly red blood cells fall to the bottom of a test tube.

Erythrocytes (ih-RITH-ruh-sytes), or red blood cells, are a part of blood. Things like inflammation or infection can lead to red blood cells clumping together, which makes them heavier than normal. This makes the cells sink down faster in a test tube. The more quickly the red blood cells fall, the higher the ESR.

Top Things to Know

• The erythrocyte sedimentation rate (ESR) blood test checks how fast red blood cells sink in a test tube.
• This test helps doctors look for inflammation and infection, and see how treatment is going.
• Kids might need to stop taking certain medicines or not eat or drink before the blood test.
• Your doctor can explain what it means if the ESR is too high.

How Can I Help My Child Prepare for a Blood Test?

To help kids get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is nervous about it, work together on ways to stay calm. Deep breathing or even imagining being in a peaceful place that makes your child feel safe and calm can help.

What Do ESR Test Results Mean?

A high ESR means that there’s likely inflammation or an infection. More tests may be needed to figure out the cause if it isn’t already known.

Your doctor will explain what the results of the ESR test mean for your child. What’s “normal” varies based on things like age and gender.

If you have questions about the ESR blood test, talk to your doctor.