Erythrocyte sedimentation rate
Synonyms and keywords: Biernacki Reaction; Sedimentation rate; Westergren ESR

# Overview
The erythrocyte sedimentation rate (ESR), also called sedimentation rate, sed rate, or Biernacki Reaction, is a non-specific, indirect measurement of the acute phase reactant concentration which is altered in conditions of inflammation. It is commonly used as a medical screening test. To perform the test, anticoagulated blood is placed in an upright tube, known as a Westergren tube and the rate at which the red blood cells fall is measured and reported in mm/h. When an inflammatory process is present, the high proportion of fibrinogen in the blood causes red blood cells to stick to each other. The red cells form stacks called 'rouleaux' which settle faster. Rouleaux formation can also occur in association with some lymphoproliferative disorders in which one or more immunoglobulins are secreted in high amounts. Rouleaux formation is, however, a physiological finding in some equidae and can be as such in felidae and suidae species, namely the horse, cat and pig respectively. The basal ESR is slightly higher in females than males and increases with age. It is also affected by the size, shape, and number of red cells, as well as by other constituents in the blood such as immunoglobulins. The ESR is increased in pregnancy, anemia, or  any cause or focus of inflammation and decreased in sickle cell anemia, polycythemia, and congestive heart failure.

# History
This test was invented in 1897 by the Polish doctor Edmund Biernacki. In 1918 the Swedish pathologist Robert Sanno Fahrus declared the same and along with Alf Vilhelm Albertsson Westergren are eponymously remembered for the Fahrus-Westergren test (in the UK, usually termed Westergren test), which uses  sodium citrate-anticoagulated specimens.

# Uses
Although it is frequently ordered, the erythrocyte sedimentation rate (ESR) is not a useful screening test.  It is only useful for diagnosing three diseases: myeloma, temporal arteritis and polymyalgia rheumatica (in which it may exceed 100 mm/hour).
It is commonly used for a differential diagnosis for Kawasaki's Disease and it may be increased in some chronic infective conditions like tuberculosis and infective endocarditis.  It is a component of the PDCAI, an index for assessment of severity of inflammatory bowel disease in children.
The clinical usefulness of erythrocyte sedimentation rate (ESR) is limited to monitoring the response to therapy in certain inflammatory diseases such as temporal arteritis, polymyalgia rheumatica and rheumatoid arthritis. It can also be used as a crude measure of response in Hodgkin's lymphoma. Additionally, ESR levels are used to define one of the several possible "adverse prognostic factors" in the staging of Hodgkin's lymphoma.
The use of the ESR as a screening test in asymptomatic persons is limited by its low sensitivity and specificity. When there is a moderate suspicion of disease, the ESR may have some value as a "sickness index."
An elevated ESR in the absence of other findings should NOT trigger an extensive laboratory or radiographic evaluation.

# Normal Values
Note: mm/hr. = millimeters per hour.
Values are increased in states of anemia, and in black populations.

## Adults
ESR reference ranges from a large study:
As an alternative the following formula may be used to give predicted values for ESR based on age and gender:

## Children
- Newborn: 0 to 2 mm/hr.
- Neonatal to puberty: 3 to 13 mm/hr.
- Newborn:                0-5 mm/hr.
- Neonatal to puberty:    0-15 mm/hr.

# Causes of increased erythrocyte sedimentation rate

## Common Causes
- Ageing
- Anemia
- Infection
- Inflammation
- Macrocytosis
- Malignancy
- Pregnancy
- Renal disease
- Technical factors (dilutional problem, increased temperature of specimen, tilted ESR tube)

## Causes by Organ System

## Causes in Alphabetical Order

# Causes of decreased erythrocyte sedimentation rate

## Common Causes
- Abnormal erythrocyte morphologies
- Hyperviscosity state
- Hypofibrinogenemia
- Hypogammaglobulinemia
- Leukocytosis
- Microcytosis
- Polycythemia
- Technical factors (dilutional problem, inadequate mixing, clotting of blood sample, short ESR tube, vibration during testing)

## Causes by Organ System

## Causes in Alphabetical Order
- Abetalipoproteinemia
- Acanthocytosis
- Anisoctyosis
- Bruton's agammaglobulinemia
- Congenital afibrinogenemia
- Congestive heart failure
- Dysproteinemia
- Hyperviscosity state
- Hypofibrinogenemia
- Hypogammaglobulinemia
- Leukocytosis
- Macrophage-activation syndrome
- Microcytosis
- Polycythemia
- Sickle cell disease
- Spherocytosis
- Technical factors (dilutional problem, inadequate mixing, clotting of blood sample, short ESR tube, vibration during testing)