Hematologic Disorders: Sickle Cell Disease.

Sickle cell disease, the most common inherited hemoglobinopathy in the United States, is a group of autosomal recessive red cell disorders resulting from hemoglobin S. Hemoglobin S forms rigid polymers when deoxygenated that give red blood cells their sickle crescent shape. Increased viscosity and cell adhesion result in vasoocclusion.

Hematologic Disorders: Bone Marrow Failure.

Pancytopenia with hypocellular bone marrow most often is caused by idiopathic aplastic anemia, but can be caused by inherited bone marrow failure syndromes, drugs, infections, nutritional deficiencies, and rheumatologic disease. Aplastic anemia (AA) can remain stable for years but can become severe or transform into a myelodysplastic syndrome, acute leukemia, or paroxysmal nocturnal hemoglobinuria. Corticosteroids and erythropoietin are ineffective for management of aplastic anemia; and granulocyte colony-stimulating factor is only indicated in severe infections that do not improve with antibiotics.

Hematologic Disorders: Blood Transfusion Products.

Until the 1980s, liberal blood transfusion criteria with limited evidence were used regardless of the patient's clinical condition. However, blood transfusion products are associated with several risks, such as infection, acute lung injury, circulatory overload, and hemolytic transfusion reactions. More restrictive transfusion criteria and patient monitoring can decrease the need for transfusions, as well as decrease morbidity and mortality rates and costs.

Hematologic Disorders: Anemia.

Anemia occurs in up to 25% of the US population. Normal hemoglobin levels vary by race, sex, and age. Classification of anemia by mean corpuscular volume guides the differential diagnosis and evaluation.