A Sed rate or erythrocyte sedimentation rate, the ESR test is a blood test that helps to reveal inflammatory activity in the body of a patient.
A sed rate is not a stand-alone diagnostic tool, however, it can help a doctor diagnose or monitor the progress of an inflammatory disease.
Moreover, when the lab technician places the blood of a patient in a tall, thin tube, red blood cells or erythrocytes gradually settle down to the bottom.
Inflammation, however, can cause the cells to clump.
As these clumps tend to be denser than individual cells, they tend to settle to the bottom more quickly.
The sed rate test helps to measure the distance red blood cells fall in a test tube in one hour.
Furthermore, the farther the red blood cells descend, the greater the inflammatory response in the immune system of the patient.
Keep on reading.
ESR Test
If a doctor suspects high levels of inflammation in the body of the patient, they may recommend an ESR blood test.
It helps to look at how quickly red blood cells sink to the bottom of the test tube, with a high rate of settlement indicating high inflammation.
Moreover, it is also called a sedimentation rate or sed rate test.
An ESR, however, does not help diagnose one specific condition.
Rather it helps a doctor to find whether a person is experiencing inflammation and what further testing may be needed.
The ESR test can also help to monitor inflammatory diseases a person already has.
How Does the ESR Blood Test Work
An ESR test helps to measure the rate at which the red blood cells, RBCs fall to the bottom of the test tube.
The blood sample for this test is measured over an hour.
When a person experiences inflammation, it can affect the RBCs in a number of ways.
First, the RBCs cling together, forming clumps and this clumping affects the rate at which RBCs sink inside the tube where a technician will place a blood sample.
Moreover, if a person has an acute infection or chronic inflammation, there may be more proteins in the RBCs.
This can cause them to settle quickly as well. The faster and further the cells sink toward the bottom of the test tube, the more it is likely that inflammation is there.
In all, the ESR is based on the rate at which the RBCs settle.
The faster this occurs, the higher the ESR of a person and the more inflammation is likely to present in the body.
Learn more about Blood Test: All You Need to Know here.
When does a doctor order ESR Test?
An ESR can help identify and measure inflammation, in general in the body of a patient.
However, it does not help pinpoint the precise cause of the inflammation.
That is why the ESR test is rarely performed alone. Instead, a doctor can likely combine this test with other tests that help to determine the cause of the symptoms.
Moreover, if a person already has an inflammatory condition, the docotr can order an ESR as part of the routine lab work to make sure that the current treatment is working.
Diagnosing Conditions that Cause Inflammation
The ESR test can help the doctor to diagnose conditions that cause inflammation, like:
- temporal arteritis
- autoimmune diseases
- cancers
- infections
Monitoring Inflammatory Conditions
The ESR test can help a healthcare professional monitor autoimmune inflammatory conditions like:
- rheumatoid arthritis, RA
- systemic lumps erythematosus, SLE
Moreover, the doctor can also order the test if a patient has some type of arthritis or certain muscle or connective tissue problems like polymyalgia rheumatic.
Symptoms that Indicate a person needs EST
It is important to note that a person may need an ESR test if they experience symptoms of inflammatory conditions like arthritis or inflammatory bowel disease, IBD.
These symptoms can include:
- joint pain or stiffness that tends to last longer than 30 minutes in the morning
- headaches, especially the ones associated with pain in the temples and vision changes
- unintentional weight loss
- pain in the shoulders, neck, or pelvis
- digestive symptoms like diarrhea, fever, blood in stool, and unusual abdominal pain.
Learn more about CBC Blood Tests: What they Show here.
Preparing for ESR Test
It is important to note that an ESR test will require little preparation.
However, it is important for the patient to tell the doctor if they are taking any medication.
The doctor may ask the patient to temporarily stop taking those medications before the test.
Certain medications can affect EST test results. For instance, steroids, nonsteroidal anti-inflammatory drugs, NSAIDs, and statins can cause possible false lower ESRs.
However, the patient should not stop taking any prescription medications unless the doctor instructs otherwise.
Procedure of the Test
This test involves a simple blood draw.
It will only take a minute or two. The following steps are:
- first, the lab technician will clean the skin over the vein
- then they will insert the needle into the vein to collect the blood
- after collecting the blood, the technician will remove the needle and then cover the puncture site to stop any bleeding
They will then take the blood sample to the lab, where they will place the blood in a long, thin tube in which it will sit for an hour.
During and after this hour, the laboratory professional processing this test will also assess how far the RBCs sink into the tube, how quickly they sink, and how many sink.
Inflammation can cause abnormal proteins to appear in the blood of the patient.
These proteins can cause RBCs to clump together in the blood.
Moreover, this will make them fall more quickly.
Other Tests
It is important to note that the doctor can also order a C-reactive protein, CRP test at the same time as the ESR test.
CRP will help measure inflammation as well, however, they can also help predict the risk of coronary artery disease, CAD, and other cardiovascular diseases.
Additionally, the doctor can also order a complete blood count test, CBC test to look for other signs of inflammation or infection.
Time required for the Results
Though wait time can vary, results from the labs that take place in the office of the doctor or a clinic will take a few business days.
Moreover, the doctor or nurse will call the patient with the results, along with the next steps.
Potential Risks
It is important to note that there are not any risks directly associated with an ESR test.
However, having blood drawn from the body can involve minimal risks. Possible complications include:
- bruising
- fainting
- hematoma
- infection
- tenderness
- lightheadedness
- inflammation of the vein
- bleeding, from very light to excessive
Moreover, the patient may also feel mild to moderate pain when th needle pricks the skin of the patient.
They may also feel throbbing at the puncture site after the test.
If the patient is uncomfortable at the sight of blood, they may also experience discomfort seeing blood drawn from the body.
Therefore, in such cases, the patient should talk with the doctor about these concerns before getting blood drawn from the body.
Two types of ESR Test
There are two methods of measuring the erythrocyte sedimentation rate. These are:
Westergen Method:
The most common ESR method is the westergen method. The blood is drawn into the Westregen-Kutz tube until the blood level reaches 2200 mm.
The tube is stored vertically and sits at room temperature for about an hour.
Moreover, the distance between the top of the blood mixture and that of the sedimentation of RBCs is measured during this test.
Wintrobe Method:
This method is similar to the westergen method, except in this method the tube is 100 mm long and thinner.
A disadvantage of this method is that it is less sensitive as compared to the Westergen Method.
Normal ESR Test Results
The norm ESR test results are measured in millimeters per hour, mm/hr. The higher the number, the higher the chances of inflammation.
Overall, it is important to note that women tend to have higher ESR levels.
While normal ESR test results are:
| Normal ESR test results | Abnormal ESR test results | |
| Females under 50 | between 0 and 20 mm/hr. | greater than 20 |
| Males under 50 | between 0 and 15 mm/hr. | greater than 15 |
| Females over 50 | between 0 and 30 mm/hr. | greater than 30 |
| Males over 50 | between 0 and 20 mm/hr. | greater than 20 |
| Children | between 0 and 10 mm/hr. | greater than 10 |
Moreover, ESR test results that are higher than 100mm/hr can indicate a more “active” disease like cancer, diabetes, or cardiovascular disease.
Understanding Abnormal ESR Test Results
An abnormal ESR result does not diagnose any particular disease. It just helps to identify potential inflammation in the body and indicates a need to look further.
Moreover, an abnormally low value can be near 0 and it is hard to state an exact value as these tests fluctuate and what is considered too low may also vary from one person to the next.
This test is not always reliable or meaningful and a number of factors can affect your results like:
- older age
- medication use
- pregnancy
- menstruation
While some cases of abnormal ESR test results can be more seriuos than others, however, many are not a huge concern.
Therefore, it is important for the patient to not worry too much if the ESR test results are abnormal.
Instead, one should work with the doctor and find out what is causing the symptoms.
They will often order follow-up tests if the ESR results are too high or low.
Causes of high ESR Test Results
There are a number of causes of high ESR test results. Some common conditions associated with a higher rate include:
- anemia
- kidney disease
- diabetes
- heart disease
- blood or vascular disease
- blood vessel inflammtion, vasculitis
- pregnancy
- obesity
- thyroid disease
- older age
- trauma
- tissue injury or ischemia, i.e. lack of blood to a tissue
- certain types of cancer, including some types of lymphoma and multiple myeloma
- systemic and localized inflammatory and infection diseases, local or widespread infection
An abnormally high ESR can indicate the presence of cancerous tumors, especially if no inflammation is found.
Autoimmune Diseases
ESR test results that are higher than normal are associated with autoimmune diseases including:
- lupus
- certain types of arthritis, including RA
- Waldenstrom’s macroglobuliemia, a rare cancer
- temporal arthritis, a condition in which the temporal artery of the patient becomes inflamed or damaged
- polymyalgia rehumatic which causes muscle and joint pain
- hyperfibrinogenemia which is too much protein fibrinogen in the blood
- allergic or necrotizing vasculitis
Infections
Some types of infections that cause ESR results to become higher than normal are bone infection, rheumatic fever, skin infection, systemic infection, and tuberculosis, TB.
Moreover, heart infections cause myocarditis, i.e. affecting heart muscles, pericarditis, affecting tissue around the heart or pericardium, and endocarditis, which affects the lining of the heart and includes the heart valves.
Causes of Low ESR Test Results
A low ESR test result can be due to:
- congestive heart failure, CHF
- hypofibroinogenemia, which is too little fibronogen in the blood
- low plasma protein, occurring in liver or kidney disease
- leukocytosis which is a high white blood cell, WBC count
- polycythemia vera, a bone marrow disorder that leads to the production of excess RBCs
- sickle cell anemia, a geneitc disease affecting the RBCs.
What are the Next Steps?
Depending on the results of the patient, the doctor may want to order additional tests like a second ESR to verify the results of the first one.
These tests can potentally help the doctor to figure out the specific cause of the inflammation in the body of the patient.
In case the patient has an underlying condition that is causing high ESR, the test can help monitor the ESR during treatment to measure how well the treatment is working.
An Underlying Condition
If the doctor suspects an underlying condition, they may refer the patient to a specialist who can properly diagnose and treat the condition.
Inflammation
If the doctor dectects inflammation, they can recommend one or more of the following:
NSAIDS like iburophen or naproxen, and corticosteroid therapy to reduce inflammation
Infection
In case a bacterial infection is causing inflammation, the doctor will likely prescribe an antibiotic to fight this infection.
