Sed Rate (ESR) by Modified Westergren Biomarker Testing
It measures inflammation indirectly by how fast red blood cells settle, with convenient ordering and Quest-based lab testing through Vitals Vault.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
Your Sed Rate (also called ESR, or erythrocyte sedimentation rate) is a broad signal of inflammation somewhere in your body. It does not point to one specific diagnosis, but it can help confirm that “something inflammatory is going on” when symptoms and other labs suggest it.
The “Modified Westergren” method is a common standardized way labs measure ESR. When you repeat the test over time, it can be useful for tracking whether inflammation is improving, worsening, or staying the same.
Because ESR is nonspecific, the most helpful way to use it is in context: your symptoms, your exam, and companion tests such as C-reactive protein (CRP), a complete blood count (CBC), and targeted autoimmune or infection testing when appropriate.
Do I need a Sed Rate BY Modified Westergren test?
You might consider an ESR test if you and your clinician are trying to sort out symptoms that could reflect inflammation, such as persistent joint or muscle pain, prolonged fatigue, unexplained fevers, new headaches, or stiffness that is worse in the morning. ESR is also commonly used when an inflammatory or autoimmune condition is already on the table and you need an objective way to follow the trend.
You may also be asked to repeat ESR if you are monitoring a known inflammatory condition (for example, certain types of arthritis or vasculitis) or checking response to treatment. In these situations, the direction of change often matters more than a single number.
If your symptoms are acute and changing quickly, ESR may lag behind what is happening in real time. In that case, your clinician may pair it with CRP, which often rises and falls faster.
This test supports clinician-directed care and follow-up planning, but it cannot diagnose a specific disease by itself.
ESR by Modified Westergren is a standardized laboratory measurement performed in a CLIA-certified lab; results should be interpreted with your clinical history and other tests, not as a standalone diagnosis.
Lab testing
Order labs to measure Sed Rate by Modified Westergren
from $16.99 at Quest Diagnostics
About 1 week
Schedule online — results typically within a week
Clear next steps
Guidance included, with follow-up care available
HSA / FSA
Eligible for pre-tax health spending accounts
Get this test with Vitals Vault
Vitals Vault lets you order an ESR (Sed Rate by Modified Westergren) test without needing to coordinate the logistics yourself. You can choose a convenient lab location and get a clear report you can share with your clinician.
If your result is out of range or you are unsure what it means, PocketMD can help you turn the number into next steps. That usually means reviewing symptoms, checking for common confounders (like anemia), and deciding whether a companion marker such as CRP or a CBC would add clarity.
ESR is often most useful when you can compare it to prior results. With Vitals Vault, it is straightforward to recheck at an appropriate interval and track the trend alongside other labs your care plan calls for.
- Order online and test at a participating Quest location
- PocketMD guidance for questions and follow-up planning
- Easy retesting to track inflammation trends over time
Key benefits of Sed Rate (ESR) testing
- Gives a broad, objective signal that inflammation may be present when symptoms are unclear.
- Helps track whether inflammation is trending up or down over time, which can support treatment monitoring.
- Adds context to pain, stiffness, fatigue, fevers, or headaches when inflammatory causes are being considered.
- Pairs well with CRP to distinguish slower, chronic patterns from faster-changing inflammation.
- Can support evaluation of certain autoimmune and inflammatory conditions when interpreted with targeted testing.
- Provides a baseline value you can compare against during flares, infections, or medication changes.
- Offers a simple, widely available blood test you can repeat consistently using the Modified Westergren method.
What is Sed Rate (ESR) by Modified Westergren?
Sed Rate (ESR) stands for erythrocyte sedimentation rate. It measures how quickly your red blood cells settle to the bottom of a thin tube over a set period of time. When inflammatory proteins in your blood increase, red blood cells tend to clump together and settle faster, which raises the ESR.
The Modified Westergren method is a standardized approach many labs use to measure ESR. Standardization matters because ESR can vary by technique, and consistent methods make it easier to compare results over time.
ESR is considered a nonspecific marker. A high result can be seen with many different conditions, including infections, autoimmune disease, chronic inflammatory disorders, and sometimes cancer. It can also be influenced by factors that are not “inflammation,” such as anemia or pregnancy. That is why ESR is usually interpreted alongside your symptoms and other labs rather than on its own.
Why ESR is “nonspecific”
ESR does not measure one inflammatory molecule. It reflects how blood proteins affect red cell settling, so many different processes can push it up or down. Your clinician uses it as a clue and a trend marker, not as a definitive answer.
ESR vs CRP
CRP (C-reactive protein) is produced by the liver in response to inflammation and often changes more quickly than ESR. ESR can stay elevated longer after an illness and can be affected by red blood cell characteristics. Many clinicians order both when they want a fuller picture.
What do my Sed Rate (ESR) results mean?
Low ESR
A low ESR is usually not concerning and often simply means there is no strong signal of systemic inflammation at the time of testing. In some cases, ESR can be lower when red blood cell counts are high or when red blood cells have shapes that settle differently. If you have significant symptoms but a low ESR, your clinician may rely more on CRP, a CBC, and targeted tests based on your history.
In-range (expected) ESR
An in-range ESR suggests there is not a strong, ongoing inflammatory signal in your bloodstream right now. This can be reassuring, but it does not rule out every inflammatory condition, especially if symptoms are localized or early. If you are monitoring a known condition, your “best” ESR is often your personal baseline, so comparing to prior results can be more informative than a single value.
High ESR
A high ESR means red blood cells are settling faster than expected, which commonly happens when inflammatory proteins are elevated. Causes range from recent infections to autoimmune or inflammatory diseases, and the degree of elevation can sometimes (but not always) correlate with how active the process is. Because ESR is nonspecific, the next step is usually to look for supporting clues: symptoms, exam findings, CRP, CBC (especially anemia), and any condition-specific tests your clinician recommends.
Factors that influence ESR (even without new disease)
ESR can rise with age and is often higher in pregnancy. Anemia can increase ESR because fewer red blood cells and altered blood properties can make settling faster, while very high red blood cell counts can lower it. Certain medications and recent illnesses can shift ESR, and chronic conditions that change blood proteins can keep it elevated even after symptoms improve. If you are trending ESR over time, try to test under similar conditions and review changes in health status and blood counts with your clinician.
What’s included
- Sed Rate By Modified Westergren
Similar tests and related topics
Frequently Asked Questions
What is a Sed Rate (ESR) test used for?
It is used as a general marker of inflammation. It can help support evaluation of inflammatory, autoimmune, or infectious processes and is often used to monitor trends over time when a condition is known or suspected.
Do I need to fast for an ESR test?
Fasting is not typically required for ESR. If your blood draw includes other tests that do require fasting (such as certain lipid or glucose tests), follow the instructions for the full set of labs you are getting.
What causes a high sed rate?
A high ESR can be caused by many things, including recent or ongoing infection, autoimmune or inflammatory disease, and other conditions that raise inflammatory proteins. It can also be elevated from non-inflammatory factors such as anemia, pregnancy, and age, which is why follow-up testing is often needed.
Can ESR be normal even if I have inflammation?
Yes. ESR is a helpful but imperfect marker. Some inflammatory conditions do not raise ESR early or consistently, and localized inflammation may not strongly affect the bloodstream. Clinicians often pair ESR with CRP and other tests when suspicion remains.
How is ESR different from CRP?
CRP is a specific protein that often rises and falls quickly with inflammation. ESR is an indirect measurement influenced by blood proteins and red blood cell characteristics, so it can change more slowly and can be affected by anemia and other factors. Many care plans use both for a more complete picture.
How often should ESR be repeated?
It depends on why you are testing. For monitoring a known inflammatory condition, your clinician may repeat it every few weeks to months, often alongside symptoms and other labs. For a one-time evaluation after an illness, repeating may not be needed unless symptoms persist or worsen.
What follow-up tests are commonly ordered with ESR?
Common companions include CRP, a complete blood count (to look for anemia or infection patterns), and condition-specific tests such as autoimmune markers when clinically appropriate. The best next test depends on your symptoms and exam findings.