Lesson 2-12

Erythrocyte Sedimentation Rate

ESR

• “Sed rate”

• Has been performed since 1930s

• Non-specific

• Indicates inflammation

ESR

• The ESR is the rate at which Erythrocytes settle

out of anticoagulated blood in 1 hour

This test is based on the fact that inflammatory and necrotic processes

cause an alteration in blood proteins,resulting in aggregation of RBCs,

which makes them heavier and more likely to fall rapidly when placed

in a special vertical test tube. The faster the settling of cells,

the higher the ESR.

Principle of ESR test

• Sedimentation of erythrocytes under standardized conditions

• In health, rate of sedimentation is slow

• In inflammatory disease, rate increases

Principle of ESR test

Factors Affecting ESR

• Plasma properties– Acute-phase proteins– Increased proteins cause rouleaux

Factors Affecting ESR

• Erythrocyte properties– Size: macrocytic cells vs microcytic– Shape: sickle cells can not aggregate,

spherocytes also yield low ESR– Number: anemia/low Hematocrit yield falsely

increased ESR

Technical Factors Affecting ESR

• Temperature

• Time

• Tube diameter and length

• Pipetting technique

• Position of tube

• Vibrations

Clinical Significance ESR• The ESR should not be used to screen

asymptomatic patients for disease.• It is most useful for diagnosis of temporal• arteritis, rheumatoid arthritis, and • polymyalgia rheumatica. • The sedimentation rate is not diagnostic

of any particular disease but rather is an indication that a

disease process is ongoing and must be investigated. • useful in monitoring the progression of inflammatory diseases;

if the patient is being treated with steroids, the ESR will

decrease with clinical improvement.

Increased ESR

• Pregnancy• Anemia• Macrocytosis• Inflammation• Cancer • Acute and chronic Infections• Multiple myeloma• Increased Fibrinogen• Increased Plasma Globulins• Tuberculosis

Decreased ESR

Sickle cellsPolycythemiaSpherocytosisMicrocytosisIncreased plasma viscosity

Methods

• Manual methods– Westergren– Wintrobe– Sediplast ESR

Methods

Sediplast ESR Test

Automated Methods

• SEDIMAT

• Vesmatic

• Zeta Sedimentation Ratio (ZSR)

Anemia Ferritin Iron Iron Saturation

Hemorrhage, acute N D D

Hemorrhage, chronic D D D

Iron-deficiency D D D

Aplastic D I I

Megaloblastic I D D

Hemolytic I I I

Sideroblastic I I I

Thalassemia major I I I

Thalassemia minor I N/I N/I

Bone marrow neoplasia

N/I I I

Uremia, nephrosis, or nephrotic syndrome

N/I D/I D

Liver disease N/I N/I N/I

Chronic diseases I D D

Table 2.6 Ferritin, Iron, and Iron Saturation Changes in Anemias N, no change; D, decrease; I, increase.

Transferrin/TIBC• Iron is contained in several components• Transferrin (also called siderophilin),

a transport protein largely synthesized

by the liver, regulates iron absorption.

Total iron-binding capacity (TIBC)

correlates with serum transferrin,

but the relation is not linear.

A serum iron test without a TIBC and transferrin

determination has very limited value

• The combined results of transferrin, iron, and TIBC

tests are helpful in the differential diagnosis

of anemia, in assessment of iron-deficiency

anemia, and in the evaluation of thalassemia,

sideroblastic anemia, and hemochromatosis

Ferritin, a complex of ferric (Fe2+) hydroxide and a protein, apoferritin, originates in the reticuloendothelial system. Ferritin reflects the body iron stores and is the most reliable indicator of total-body iron status. A bone marrow examination is the only better test. Bone marrow aspiration may be necessary in some cases, such as low-normal ferritin and low serum iron in the anemia of chronic disease.The ferritin test is more specific and more sensitive than iron concentration or TIBC for diagnosing iron deficiency.

Vitamin B12(VB12)Vitamin B12 (VB12), also known as the antipernicious anemia factor, is necessary for the production of RBCs. It is obtained only from ingestion of animal protein and requires an intrinsic factor for absorption. Both VB12 and folic acid depend on a normally functioning intestinal mucosa for their absorption and are important for the production of red blood cells. Levels of VB12 and folate are usually tested in conjunction with one another because the diagnosis of macrocytic anemia requires measurement of both.This determination is used in the differential diagnosis of anemia and conditions marked by high turnover of myeloid cells, as in the leukemias. When binding capacity is measured, it is the unsaturated fraction that is determined. The measurement of unsaturated VB12–binding capacity (UBBC) is valuable in distinguishing between untreated polycythemia vera and other conditions in which there is an elevated Hct.

Folic acid is needed for normal RBC and WBC function and for the production of cellular genes. Folic acid is a more potent growth promoter than VB12, although both depend on the normal functioning of intestinal mucosa for their absorption. Folic acid, like VB12, is required for DNA production. Folic acid is formed by bacteria in the intestines, is stored in the liver, and is present in eggs, milk, leafy vegetables, yeast, liver, fruits, and other elements of a well-balanced diet.This test is indicated for the differential diagnosis of megaloblastic anemia and in the investigation of folic acid deficiency, iron deficiency, and hypersegmental granulocytes. Measurement of both serum and RBC folate levels constitutes a reliable means of determining the existence of folate deficiency. The finding of low serum folate means that the patient’s recent diet was subnormal in folate content, that the patient’s recent absorption of folate was subnormal, or both. Low RBC folate can mean either that there is tissue folate depletion owing to folate deficiency requiring folate therapy or, alternatively, that the patient has primary VB12 deficiency that is blocking the ability of cells to take up folate. Serum levels are commonly high in patients with VB12 deficiency because this vitamin is needed to allow incorporation of folate into tissue cells. For thoroughness, the serum VB12 should also be determined because more than 50% of all patients with significant megaloblastic anemia have VB12 deficiency rather than folate deficiency.