About Sed Rate Blood Test Results

Sed rate or EST is the common name for an erythrocyte sedimentation rate. This blood test is drawn using a needle into a lavender stoppered tube that has the additive EDTA in it to prevent the blood sample from clotting. The Sed rate test indirectly measures inflammation in the body and is considered non specific since it can not pinpoint where in the body the inflammation is occurring. Sed rates are commonly used along with other tests to present a complete clinical picture.

What it Measures

• When erythrocytes, or red blood cells, clump together to form a column like structure it is called sedimentation. This occurs due to a change in the plasma proteins and this usually occurs slowly since normal red cells do not form this column or rouleaux. Sed rates actually measure the rate the red cells settle out of anticoagulated blood in one hour. The faster the red cells settle, the higher the sed rate result will be.

The Science Behind It

• The test is based on the fact that inflammation causes changes in plasma proteins that can result in the sedimentation of red cells. The protein changes cause the red cells to clump. The clumping makes them heavier and more likely to form the rouleaux formation when placed in a test tube in a vertical position. It is most often used to diagnose arthritis and arteritis.

Abnormal Results

• Abnormal results can be seen in many disorders. High sed rates are frequently seen in infections such as pneumonia, lupus, inflammatory diseases, certain types of cancers, heavy metal poisoning, and in myocardial infarctions. Abnormally high levels can also be seen in rheumatoid and other types of arthritis, hyper and hypothyroidism, gout and some types of anemia. Obviously, a wide variety of conditions can be indicated by an elevated erythrocyte sedimentation rate.

Things that May Interfere

• There are certain things that can negatively affect the specimen. If the sample is left to stand for more than 24 hours, the sed rate begins to decrease. Conversely, if the sample is refrigerated, the rate begins to increase. The sample should be allowed to warm to room temperature before being run if it has been refrigerated. Pregnancy, menstruation and certain drugs can also skew the results to be high. A high white blood cell count, high blood sugar or sickle cell anemia are just some of the conditions that can cause a very low sed rate to occur.

Things to Remember

• Sed rates should always be performed in conjunction with other tests. Such tests as C-reactive protein, complete blood count and other general screening tests may be drawn at the same time. As always, it is imperative to speak to your physician to interpret the results. In women between the ages of 70 and 89 it is possible to see extremely high levels for no apparent reason. This is not a blood test that alone can diagnose any condition, rather it is part of a battery of tests that should be added to a physical exam to assist a physician in diagnosing a patient.