Hematology is a branch of internal medicine that deals with diseases affecting the production of blood and its components. Hemoglobin (cells that carry oxygen to various organs), White blood cells (infection fighting cells of the body) and Platelets (cells that prevent bleeding) form the major components of blood and are produced in the bone marrow.
An impaired production of the above-mentioned cells could lead to an anemia (low hemoglobin), thrombocytopenia (low platelets) or a neutropenia (low white blood cells). The reduced production may either be due to a stem cell defect in its production or an excessive destruction due to several reasons. Sometimes disorders could involve more than one cell lines and is accompanied by a very empty bone marrow. Such disorders are called aplastic anemia and is often rapidly fatal, if not addressed soon enough. In contrast, several blood disorders are due to an excessive production of the blood cells and they are called as myeloproliferative disorders.
Some other disorders include that of the spleen (splenomegaly i.e an increase in the size of the spleen due to any cause), lymphomas that signify tumours of the draining lymph nodes and may involve the bone marrows, other blood cancers such as leukemias and plasma cell (a subtype of white blood cell) dycrasias like multiple myelomas etc. Other important blood components include blood proteins that maintain fluidity of the blood and few examples of such diseases include like hemophilias, thrombophilias. etc.