Erythrocyte Sedimentation Rate (ESR) for Ophthalmology

Summary: • Erythrocyte sedimentation rate (ESR) - rate in mL/hr of erythrocyte sedimentation o From the 1800s o How fast red blood cells (RBCs) sediment in a tube over an hour, in millimeters • Normal sedimentation rate o RBCs have a charge, and a potential is generated by that charge that keeps the RBCs apart because the charges repel o This negative charge = zeta potential • Created by sialic acid residues on the surface of RBC membranes • Useful because RBCs have to pass single-file through capillary beds o RBCs do not clump together because their charges repel • Abnormal (increased) sedimentation rate o Something is decreasing the zeta potential, allowing RBCs to collect into the Rouleaux formation in a test tube • Rouleaux formation = stack of RBCs, like a stack of coins • Problems/processes that may cause increased sed rate o Inflammatory, infectious, neoplastic malignancy (i.e. multiple myeloma) • Inflammation of any kind -> release acute phase reactants (i.e. c-reactive protein, increased platelet count) o Good to order C-reactive protein, platelet count in addition to the ESR to make an informed clinical decision o Age and Gender • Proteins accumulate in blood as we age • Empiric formula o For women: (age + 10)/2 o For men: age/2 • 40 is too high for an older patient • Consider testing ESR for any older patient with a neuro-ophthalmic symptom o Neuro-ophthalmic problems (esp. in elderly) • Giant cell arteritis • Vision loss/double vision • Amaurosis fugax • Etc. • ESR is not specific o Renal failure o Diabetes o Inflammation/infection o Neoplastic malignancy (I.e. multiple myeloma) o Can have normal ESR rate but still have giant cell arteritis