Hematological Disorders

Original Editor - Reem Ramadan Top Contributors - Lucinda hampton, Reem Ramadan, Admin, Elaine Lonnemann, Kim Jackson, Uchechukwu Chukwuemeka and Vidya Acharya

Overview

Hematologic disorders refer to a vast array of disorders affecting the blood, with new ones being still being discovered. These disorders may affect the quantity and function of the blood cells or proteins in both the immune system and the blood clotting system. Hematologic disorders, may be inherited (e.g., hemophilia and sickle cell disease ) or acquired (venous thromboembolism)

Below are some ways these disorders can be classified.

1. Blood disorders causing a decrease the number of cells in the blood:

• Anemia: A decreased number of red blood cells
• Leukopenia: A decreased number of circulating white blood cells (leukocytes) especially the granulocytes (the term leukopenia often used interchangeably with neutropenia), as a result of reduced production of white blood cells or increased utilization and destruction, or both. Infection, drugs, malignancy, megaloblastosis, hypersplenism and immunoneutropenia are responsible for most cases of neutropenia
• Thrombocytopenia: A decreased number of platelets ie a platelet count that falls below the lower limit of normal, i.e., 150000/microliter (for adults). Platelets are blood cells aiding blood clotting and wound healing. Risks associated with thrombocytopenia range from no risk at all to bleeding risks and thrombosis.

2. Blood disorders causing the numbers of blood cells to increase:

• Erythrocytosis: a blood disorder characterised by an increased red blood cell mass. The most common causes of erythrocytosis are acquired. Causative factors include diseases and conditions that are accompanied by hypoxaemia or overproduction of erythropoietin. Infrequently, erythrocytosis has a known genetic background, eg. polycythaemia vera and familial erythrocytosis.
• Leukocytosis: increased number of white blood cells. Leukocytosis is a common finding with a broad differential diagnosis and is usuallt subdivided according to the type of WBC contributing to the elevation. Infection, inflammation, allergic reactions, malignancy, and hereditary disorders are all common causes of leukocytosis.
• Thrombocytosis or thrombocythemia: increased number of platelets. Thrombocytosis can occur as a primary event accompanying hematological diseases or as a secondary event. It is important to determine the cause of and prevent thrombosis.

3. Blood disorders affecting proteins within the blood cells or blood plasma eg:

• Hemoglobin.
• Immune system proteins (ie immunoglobulins) are glycoproteins that your immune cells make to fight off bacteria, viruses, fungi, parasites, cellular antigens, chemicals, and synthetic substances. Immunoglobulins constitute about 20% of the protein in plasma
• Blood clotting factors. Clotting factors are enzymes in normally present in the blood in inactive forms (all proteins, except factor IV) within the clotting cascade necessary to form cross‐linked fibrin.

4. Bleeding Disorders: the three most common hereditary bleeding disorders are hemophilia A , hemophilia B (factor IX deficiency) and von Willebrand disease.

Clinically Relevant Anatomy and Pathological Process

See and participate in this link Haematological Conditions Programme

Diagnostic Procedures

Hematology laboratories have a major role in providing diagnostic testing for a vast range of blood disorders. Disorders that we cannot diagnose or have an uncharacterized pathogenesis, are challenging and need be addressed by ongoing research. A lot of people extensively evaluated for bleeding problems often have completely normal test findings, but have significant bleeding problems mimicking eg von Willebrand disease or platelet function disorders.