Erythrocyte Sedimentation Rate (ESR) Test
Overview
The erythrocyte sedimentation rate (ESR), also called sed rate, is a simple blood test often used to look for inflammation in the body. The ESR test does not pinpoint a specific disease but gives helpful clues for further checks. It is especially helpful for monitoring changes in ongoing conditions and assessing the bodyโs response to treatment.
It is typically used alongside other blood tests to help spot or monitor several health problems. During the test, a health professional takes a blood sample and places it in a tall, narrow tube. Red blood cells begin to sink to the bottom over about an hour.
If there is inflammation, proteins cause these cells to stick together and settle more quickly. The distance the red blood cells travel down the tube is measured in millimeters per hour (mm/hr). A larger distance usually means more inflammation in the body.
Key Facts About ESR:
- Measures how fast red blood cells settle.
- Used alongside other blood tests.
- Can help spot or monitor several health problems.
The ESR test does not pinpoint a specific disease but gives helpful clues for further checks.
Reasons for Testing
A sed rate test often helps detect inflammation in the body. Doctors may order this test when someone has unexplained fever, joint pain, or muscle aches. The results can help check for health problems like rheumatoid arthritis, polymyalgia rheumatica, or giant cell arteritis.
This test also helps track if inflammation improves or worsens during treatment. However, it does not show the exact cause, so doctors often use it along with other tests, like the C-reactive protein (CRP) blood test.
Further Details
The sed rate test can provide clues in many conditions, such as lupus, infections, vasculitis, and cancer. Doctors may also use it for diseases like inflammatory bowel disease (IBD), tuberculosis, adult Still disease, granulomatosis with polyangiitis, juvenile idiopathic arthritis, fibromyalgia, and optic neuritis.
Preparation Steps
No fasting is required before this blood test. Patients should continue normal eating and drinking. If you are being checked for liver, kidneys, heart disease, or diabetes, share current medications or supplements with the rheumatologist.
What to Expect During the Procedure
A healthcare provider will draw a small amount of blood from a vein in your arm using a needle. The process usually takes just a few minutes and uses a test tube to collect the blood.
The lab then measures the sedimentation rate from the sample. Some people notice minor tenderness at the site, but you can resume normal activities soon after the blood test.
Test Outcome Details
Sed rate test results appear in millimeters per hour (mm/hr), measuring the distance red blood cells settle in one hour. Several factors, including age and sex, can change these readings. Infection and injury may also lead to higher or lower rates.
Other influences include anemia, pregnancy, kidney or thyroid conditions, and certain cancers like multiple myeloma. Some conditions, such as hypofibrinogenemia (low fibrinogen) or polycythemia (high red cell count), can make results less reliable. In these cases, the sed rate could appear lower even in the presence of disease.
Doctors may use other tests, like C-reactive protein, alongside the sed rate to monitor inflammation more accurately. Always consider results with other test findings and the patient’s health status. The sed rate mostly helps track changes over time, rather than diagnose a specific illness.
| Factor | Possible Effect on Sed Rate |
|---|---|
| Anemia | May increase sed rate |
| Polycythemia | May decrease sed rate |
| Low fibrinogen | May decrease sed rate |
| Inflammation or Infection | May increase sed rate |
| Pregnancy | May increase sed rate |
Speak with a healthcare professional to better understand what your sed rate results mean in the context of your health.
