The causes of blood disorders vary depending on the part of blood they affect, reports WebMD. Malaria, which affects red blood cells, has a different cause than lymphoma, which affects white blood cells.
Red blood cells are the part of blood that carries oxygen, states WebMD. They can become infected with the malaria parasite from mosquito bites, which causes them to burst and results in fever, chills and death. Having too many red blood cells is called polycythemia vera, which sometimes causes blood clots. Having too few blood cells is called anemia; it has many causes, including chronic kidney disease, an overactive immune system, inability of bone marrow to produce enough red blood cells, and the sickle cell mutation.
White blood cells are the part of blood that fights infections, according to WebMD. Cancers such as lymphoma, leukemia, multiple myeloma and myelodysplastic syndrome affect this type of cell. Platelets are the part of blood that forms clots; platelet disorders are grouped under the term thrombocytopenia. The blood thinner heparin can cause thrombocytopenia, but other causes are unknown as of 2015. Other blood disorders include sepsis, which results from infections, and hereditary conditions, such as hemophilia and von Willebrand disease, which affect blood proteins.