Fevers, muscle disorders and some forms of arthritis can cause high sed, or erythrocyte sedimentation, rates. High sed rates can be warning signs for conditions with the kidneys or thyroid, and abnormal rates can also be due to anemia, pregnancy or cancer.
A sedimentation test measures in millimeters per hour the settlement of red blood cells in a test tube. A higher number may indicate an inflammation in which the immune system or liver produces specific proteins that cause healthy red cells to cling to one another and fall more rapidly.
While the sed rate test is not used to make exact diagnoses, it can be used with additional tests to monitor and detect other issues such as autoimmune deficiencies, certain cancers and infections in bones or other organs. Viral infections, lupus, appendicitis and tuberculosis may also cause elevated sed rates, but these illnesses require further testing to correctly determine the cause of the inflated results. Sed rates are also used to monitor how well a condition is responding to a prescribed treatment.
Low sed rates can also indicate problems. Sickle cell anemia, leukemia, high blood sugar, low plasma protein and congestive heart failure can all result in lowered sed rates.