Uses of Erythrocyte Sedimentation Rate in Allergy/Immunology

Abstract

The erythrocyte sedimentation rate (ESR), one of the original tests of modern medicine, is a relatively simple procedure that continues to be used in evaluating medical conditions. Its function in the allergist/clinical immunologist's practice is to assess patients with an unusual presentation of a normally encountered condition for an underlying disorder, e.g., a severe asthmatic with Churg Strauss syndrome. It is also used to identify potential etiologies of some disorders, such as vasculitis causing chronic urticaria. It is neither completely sensitive nor specific for diagnosing any disorder; thus, it is adjunctive to the history, physical exam, and other laboratory and radiological studies. The ESR does not have a role in assessing uncomplicated atopic conditions. (Pediatr Asthma Allergy Immunol 2002; 15[3]: 167-171.) METHODOLOGY T HE NATIONAL COMMITTEE FOR CLINICAL LABORATORY STANDARDS recommends the Westergren methodas the standard to determine the ESR. 1 This technique has not significantly changed over the last 70 years. 2 Four milliliters of whole blood is mixed with 1.0 mL of sodium citrate. This mixture is added to a Westergren tube, a vertical 2.5-mm diameter tube that is 30-cm long with the top 20 cm calibrated from 0 to 200 mm. The tube is filled to the zero mark at room temperature. At 60 minutes the upper level of the settled red blood cells (RBCs) is measured in millimeters from the zero mark. This value, in millimeters per hour, is the erythrocyte sedimentation rate (ESR). The modified Westergren method uses the same technique, but ethylenediaminetetraacetic acid (EDTA) is used as an anticoagulant to permit assaying other hematologic tests with the same sample. A micro-ESR method useful in newborns utilizes a similar technique but only requires 0.2 mL of blood. 1 The normal Westergren ESR is 0-2 mm/hr in a newborn, 0-10 mm/hr in a child, 0-15 mm/hr in a female adult, and 0-10 mm/hr in a male adult. 3 The ESR normally increases with age. For men, normal results are less than 30-40 mm/hr for ages older than 85 years and 30 mm/hr or less for ages 50-85 years. Similarly, for normal women, results are 42 mm/hr or less for ages older than 85 years and 30 mm/hr or less for ages 50-85 years. 1,4 A rule of thumb for the normal ESR in men is age in years divided by 2, and in women, age in years, divided by 2 plus 5-10.