Summary :
Sedimentation Rate is a non-specific indicator of inflammation or other underlying health conditions. This article explains this blood test, show its importance and its limites and how interpret the results
◉ What is sedimentation rate ?
The sedimentation rate (ESR) is the rate at which red blood cells (erythrocytes) fall into a vertical graduated tube left to rest (sedimentation). Its value corresponds to the height, in mm, of plasma above the formed elements of the blood after incubation for 1 hour.
This rate evolves in parallel with the concentrations of proteins in the blood , especially in the event of inflammation where the levels of inflammatory proteins (fibrinogen or immunoglobulins) increase. The positive charges of these proteins facilitate the agglutination of red blood cells, these agglutinations are denser than the individual cells, therefore, they settle more quickly to the bottom.
The sed rate test is not a stand-alone diagnostic tool, but it can help your doctor diagnose or monitor the progress of an inflammatory disease.
Westergren tube used to measure ESR
◉ Sedimentation rate normal range
The ESR measured is expressed in millimeters (mm) (corresponds to the distance in millimeters that the red blood cells have traveled in one hour). Although "normal" ESR values vary from lab to lab, it is generally accepted that :
- Men: < 15mm
- Woman: < 20mm
- Child: < 10mm
- Newborn: < 2mm
Test results may vary depending on your age (increases with age), gender, pregnancy, technical factors (dilution problem, high temperature, tube inclination), etc.
Note : For some references, the normal value is < 20 mm for men and < 25mm for women.
◉ Sedimentation rate Interpretation
High sedimentation rate
Finding an isolated sedimentation rate increase is of little value and difficult to interpret. An elevation of ESR above 15mm (20mm for women) this may mean that your body is having an inflammatory reaction to something but will not identify its location or cause.
There are several causes of a high sedimentation rate:
- Arthritis
- Vasculitis
- Inflammatory bowel disease
- Bacterial infection
- Hyperlipoproteinemia
- Hypergammaglobulinemia
- Hypoalbuminemia
- Macrocytosis
The value of sedimentation Rate is a piece of information that can help your doctor check your condition by considering your history, symptoms, and the results of your other diagnostic tests.
Low sedimentation rate
◾ Among the causes of a drop in sedimentation rate:
- Leukocytosis: high white blood cell count
- Polycythemia: high number of red blood cells in the blood.
- Sickle cell disease
- Anisocytosis
- Acanthocytosis
- Microcytosis
- Technical factors (dilution issues, insufficient mixing, sample coagulation, short tube)
- Low fibrinogen
- Hypogammaglobulinemia
- Taking certain anti-inflammatories in high doses
◉ Sedimentation rate assay
In general, there are no special preparations to make before the test, it is a routine blood test that can be done at any time and does not require no fasting, unless your blood sample will be used for additional testing (e.g. blood sugar).
A healthcare professional will take a sample of blood from a vein in your arm, using a small needle.
Several options are available:
- The Westergreen technique, reference manual technique ;
- Techniques derived from the reference technique using particular devices.
- Automated ESR Analyzers are modern instruments that utilize advanced technology to measure the sedimentation rate.
Westergreen Technique
◉ Sedimentation rate and Covid-19
Like all other infections, Covid-19 may be accompanied, regardless of the severity of the disease, by an increase in sedimentation rate.
◉ Sedimentation rate and pregnancy
The sedimentation rate of erythrocytes is strongly influenced by gestational age and hemoglobin concentration.
ESR increases, during pregnancy, in parallel with gestational age and can reach, according to a study, 70mm/h in the second half of pregnancy.
◉ Why is ESR higher in women than in men?
The normal ESR is higher in women than in men, mainly due to a lower hemoglobin level in women.
◉ What other tests could I have with this test ?
- CRP : Like ESR, this test measures inflammation.
- Antinuclear antibody test : Mesure les auto-anticorps qui attaquent vos cellules. Ceci est important dans le diagnostic de certaines maladies auto-immunes.
- Rheumatoid factor : This test is done to help diagnose and monitor rheumatoid arthritis.
◉ Difference Between CRP and Sedimentation Rate (ESR)
sedimentation rate measures the rate at which red blood cells are deposited, while CRP is a protein produced by the liver in response to inflammation. Both can be useful markers of inflammation, but CRP is generally considered a more specific and sensitive marker than sedimentation rate.
Relative to the red blood cell sedimentation rate, C-reactive protein levels increase and decrease rapidly with the onset and removal of the inflammatory stimulus, respectively.
🏿 Frequently Asked Questions
Q: Why does ESR increase with age?
A: This increase is related to the increase in fibrinogen levels with age.
Q: When should I be worried about my SV?
A: ESR levels above 100 mm/h could indicate a more “active” disease, such as cancer, diabetes, or cardiovascular disease.
Q: What are the factors that can influence the VS result ?
A: Many factors can affect your results, such as: age, use of medication, pregnancy, menstruation. etc