Disorder		Most common clinical features	Features of peripheral blood smear	Laboratory tests
Congenital conditions
Homozygous sickle cell disease (hemoglobin SS disease)		Vaso-occlusive crises, splenomegaly, cerebrovascular accidents, priapism, hand-foot syndrome, acute chest syndrome	Sickle cells	Hemoglobin electrophoresis
Heterozygous sickle hemoglobin C disease (hemoglobin SC disease)		Generally similar to homozygous sickle cell disease, except associated with fewer infections, less hemolysis and fewer crises, but more retinopathy and aseptic necrosis	Sickle cells, target cells	Hemoglobin electrophoresis
Hereditary spherocytosis		Childhood anemia, splenomegaly, jaundice	Spherocytes	Osmotic fragility test
Hereditary elliptocytosis		Variable: asymptomatic carrier state to severe hemolysis	Elliptocytes	25 percent or more of red blood cells elliptocytic on peripheral blood smear
G6PD deficiency		Transient hemolysis following exposure to oxidative drug	Normal	G6PD activity
Pyruvate kinase deficiency		Variable: severe anemias in newborns to no symptoms in adults	Normal	Red blood cell P-50 level (screening); red blood cell pyruvate kinase activity (confirmatory)
Acquired conditions
Microangiopathic disorders			Thrombocytopenia, schistocytes
	Disseminated intravascular coagulopathy	Bleeding and/or intravascular hemolysis		Hypofibrinogenemia; increases in partial thromboplastin time, prothrombin time, fibrin split products and thrombin time
	Hemolytic-uremic syndrome	Fever, jaundice, bleeding, central nervous system changes, renal failure; generally occurs in children		Increased creatinine level
	Thrombotic thrombocytopenic purpura	Purpura, fever, central nervous system changes; generally occurs in adults
Mechanical hemolysis		Mild to moderate anemia; frequently, iron deficiency, second-degree chronic urinary loss; history of heart valve replacement or valvular disease	Schistocytes	None
Paroxysmal nocturnal hemoglobinuria		Recurrent abdominal pain, vomiting, headache, eye pain; venous thromboses; leads to iron deficiency anemia	Normal	Sucrose hemolysis (screening); Ham's test (confirmatory)