Hematology: Erythrocyte Sedimentation Rate

the distance in millimeters that red cells fall per unit of time (1 hour)

erythrocyte sedimentation rate (ESR)

Red cells fall (slower/faster) in certain disease states, especially inflammatory disorders

faster

What are the 3 stages of sedimentation for an ESR and their times?

1) initial aggregation: 10 minutes

2) fast settling: 40 minutes

3) final packing period: 10 minutes

What is the standard reference range for ESR?

0-20 mm/hr

What is the difference between Wintrobe and Westergreen tubes?

Wintrobe is shorter and does not contain isotonic saline

Westergreen is longer and uses isotonic saline

What 3 factors affect EST testing?

plasma factors, red cell factors, mechanical and technical factors

What plasma factors elevate and slow down ESR?

elevate (all coat RBCs to promote rouleaux)

- increased fibrinogen

- increased immunoglobulins

- increased cholesterol

slow down (make plasma thicker, "stickier")

- increased albumin

- increased lecithin

What red cell factors elevate and slow down ESR?

elevate

- low red cell counts (anemia) (not as many that have to fall down)

- large red cells, macrocytes (heavy)

slow down

- irregularly shaped cells (can't slide past eachother)

- small red cells, microcytes

- increased red cell counts (polycythemia) (more cells to fall down)

What mechanical factors elevate and slow down ESR?

elevate

- length of the tube or column

- position of the tube

- choice of anticoagulants

- high temp

slow down

- low temp

What are the four sources of error when performing ESR tests?

1) tilting the tube

2) bubbles in the tube (sample will stop at bubbles)

3) temperature (needs to be RT)

4) timing (must be read at 1 hour mark)

How will tilting the ESR tube affect results?

every degree tilited = 1 mm off

What conditions elevate the ESR result? What do they have in common?

*cause an inflammatory response*

pregnancy, infections, arthritis, tumors, tissue damage, myocardial infarction, nephritis, hepatitis, multiple myeloma, macroglobulinemia, hyper and hypothyroidism

What 3 disorders shorten the ESR?

polycythemia vera (excess RBCs produced)

hereditary spherocytosis

sickle cell anemia