A CBC test can help your doctor detect the following diseases and ailments: Various anemia types. Bone marrow disorders. Severe dehydration. Autoimmune disorders. Internal inflammation. Low platelets count. Lymphoma. Hemoglobin abnormalities. Sickle cell disease or sickle cell anemia. Thalassemia. Vitamin deficiencies. Cancer, especially when it has spread to the bone marrow. Myeloproliferative neoplasms. Myelodysplastic syndrome. Other blood -related infections.