(G6PD) Deficiency and Exercise

Home , Hemolytic anemia

POPULATION-SPECIFIC CONCERNS Kathleen M. Laquale, PhD, ATC, LSD, Report Editor Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency and Exercise

Gregory R. Waryasz, BS, CSCS • Tufts University

G6PD Deficiency letic performance, he or she is in a unique GLUCOSE-6-phosphate dehydrogenase situation to recognize the early symptoms (G6PD) deficiency is the most common of anemia. The athletic trainer can obtain a enzyme deficiency worldwide, which affects dietary intake history that includes all fluids, approximately 400 million individuals, or supplements, and foods to identify any 7% of the world population.1,2 The most deficiency in intake of calories, protein, car- commonly affected ethnic groups have bohydrates, fluids, iron, vitamins, and other African, Asian, Mediterranean, and Middle minerals. A sleep history can be obtained to Eastern ancestry, which corresponds to document how long the athlete sleeps each the geographic distri- night, if the athlete naps during the day, if bution of malaria.1,3 the athlete has insomnia, and any activities Key PointsPoints Approximately 10% the athlete does in bed. If an athletic trainer of African-American believes an athlete is excessively fatigued, Glucose-6-phosphate dehydrogenase males are believed to despite adequate sleep habits, sufficient (G6PD) deficiency is a common genetic have some degree of hydration, and consumption of a proper diet, enzyme deficiency. G6PD deficiency.1 a possible cause of the symptoms could be G6PD deficiency (Table 2). G6PD deficiency causes anemia due to G6PD deficiency leads to erythrocyte oxidative damage to the erythrocytes. Biochemistry (red blood cell) hemo- Early referral of a symptomatic individual lysis that is due to oxi- G6PD functions to catalyze the conversion can lead to improved management. dative damage to its of nicotinamide adenine dinucleotide phos- membrane and hemo- phate (NADP) to the reduced form NADPH globin. The erythro- in the pentose phosphate pathway.1,3 Figure cytes lyse leading to anemia is defined as 1 illustrates the biochemical pathway of a qualitative or quantitative deficiency of glucose metabolism within the erythrocyte. hemoglobin. Common symptoms of anemia Oxidative stress results in accumulation are general fatigue, fatigue during exercise, of H2O2, which cannot be converted into shortness of breath on exertion, or poor H2O without an adequate supply of NADPH. concentration. Anemia can lead to heart Because erythrocytes lack mitochondria, the palpitations, diaphoresis, and heart failure. pentose phosphate shunt is their only source (See Table 1 for a glossary of terms.) of NADPH,3 and they are highly susceptible Because the athletic trainer has the to oxidative damage.4 A G6PD deficiency opportunity to observe an athlete on a daily results in varying levels of disease and its total basis and note changes in mood and ath- absence is incompatible with life.5

26  may 2009 Athletic Therapy Today Table 1. Glossary of Medical Terminology Anemia Quantitative or qualitative deficiency of hemoglobin, a component in red blood cells that carries oxygen. “Bite cells” Red blood cells appearance of having a “bite” taken out of one side of the cell. Seen in hemolytic disorders with Heinz bodies. The most common cause is G6PD deficiency. Cholelithiasis Formation of gallstones within the gallbladder. Chronic nonspherocytic Group of genetically transmitted blood disorders due to premature destruction of red anemia blood cells during normal erythrocyte development. An anemia develops if production cannot replace destroyed cells. The anemia varies from a mild to a transfusion dependent anemia. Conjugated/direct Bilirubin that has been chemically bound to glucuronide in the liver. It is excreted into bile. bilirubin Coomb’s test Laboratory test to determine if antibodies are present in the blood that can destroy red blood cells. Diaphoresis Symptoms of excessive sweating. Erythrocyte Also known as red blood cell. Haptoglobin A blood protein that binds free hemoglobin. Clinically it can be used as a screening and monitoring tool of intravascular hemolytic anemia. Heinz body Red blood cell inclusions consisting of denatured hemoglobin Hemoglobin Iron containing oxygen transport protein in red blood cells. Hemoglobinuria Presence of hemoglobin in the urine. Hemolysis Breaking open of red blood cells, releasing hemoglobin. Jaundice Yellowish discoloration of skin, eyes, and mucous membranes due to increased bilirubin. Kernicterus Damage to the brain in infants due to increased levels of unconjugated bilirubin. Myalgias Muscle pain. Myoglobinuria Presence of myoglobin in the urine suggestive of muscle damage. Oxidative damage Inability of a biological system to detoxify reactive oxygen species resulting in cellular damage. Peripheral blood smear A microscope slide made from a drop of whole blood that can be examined for hematologic or infectious processes. Reticulocytes (Reticulocy- Immature red blood cells. Reticulocytosis is a condition in which there is an elevation of tosis) reticulocytes. Sickle Cell Anemia A hematologic disorder where red blood cells have an abnormal, rigid, and sickled shape. The morphology of the cell predisposes the individual to a variety of complications. Splenomegaly Enlarged spleen suggestive of increased workload of the spleen as seen in hemolytic ane- mias. Unconjugated/indirect Bilirubin that has not been conjugated in the liver. This fraction of bilirubin is indicative of bilirubin hemolysis of inability of the liver to clear bilirubin. X-linked disorder Sex linked genetic inheritance through the X chromosome. Most conditions are more common in males due to males usually having only one X chromosome and females usually having two X chromosomes. Note. Information compiled from Harrison’s Principles of Internal Medicine (17th ed).14

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