Diagnostic Strategy in a Suspected Red Cell Enzymopathy

Hereditary red blood cell disorders in middle eastern patients

Hereditary disorders of erythrocytes are common in many areas of the world, including the Middle East. In some regions of the Middle East more than 10% of the population are carriers of a gene for one of these conditions. When patients from the Middle East seek medical care in the West, an unrecognized but clinically important erythrocyte disorder can result in serious complications during routine medical care, such as a drug-induced hemolytic crisis. This article reviews the most important and most common inherited red blood cell disorders in Middle Eastern patients, including glucose-6-phosphate dehydrogenase deficiency, the thalassemias, and sickle cell disorders. We discuss when to suspect such conditions, how to determine their presence, and how to avoid potential complications related to them. Although a detailed discussion of treatment of erythrocyte disorders is beyond the scope of this article, some general management principles are described.

Yield of reticulocyte counts and blood smears in term infants

Reticulocyte counts and blood smears are commonly recommended to evaluate jaundice in newborns. To investigate the results and diagnostic yield of these tests, we reviewed a computerized database and medical records of term newborns who had reticulocyte counts (n = 799) or blood smears (n = 781) within the first week after birth at two hospitals. Nearly a threefold difference was noted in reticulocyte counts between the two hospitals (median 8.0% vs 2.8%; P < .0001), apparently due to differences in laboratory methods. Among the patients with "abnormal" reticulocyte counts or blood smears (n = 192), isoimmunization was diagnosed in 54, presumed hemolysis of unknown etiology in two, G6PD deficiency in one, and pyropoikilocytosis in one. We conclude that better standardization of reticulocyte counts is needed. When ordered as screening tests for hemolysis in jaundiced infants, reticulocyte counts and blood smears seldom lead to diagnoses of hemolysis other than isoimmunization.