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Bone marrow is the spongy tissue inside some of your bones, such as your hip and thigh bones. It contains stem cells. The stem cells can develop into the red blood cells that carry oxygen through your body, the white blood cells that fight infections, and the platelets that help with blood clotting.

With bone marrow disease, there are problems with the stem cells or how they develop:

• In leukemia, a cancer of the blood, the bone marrow makes abnormal white blood cells
• In aplastic anemia, the bone marrow doesn't make red blood cells
• In myeloproliferative disorders, the bone marrow makes too many white blood cells
• Other diseases, such as lymphoma, can spread into the bone marrow and affect the production of blood cells

Causes of bone marrow diseases include genetics and environmental factors. Tests for bone marrow diseases include blood and bone marrow tests. Treatments depend on the disorder and how severe it is. They might involve medicines, blood transfusions or a bone marrow transplant.

Your blood is living tissue made up of liquid and solids. The liquid part, called plasma, is made of water, salts and protein. Over half of your blood is plasma. The solid part of your blood contains red blood cells, white blood cells and platelets.

Blood disorders affect one or more parts of the blood and prevent your blood from doing its job. They can be acute or chronic. Many blood disorders are inherited. Other causes include other diseases, side effects of medicines, and a lack of certain nutrients in your diet.

Types of blood disorders include:

• Platelet disorders, excessive clotting, and bleeding problems, which affect how your blood clots
• Anemia, which happens when your blood does not carry enough oxygen to the rest of your body
• Cancers of the blood, such as leukemia and myeloma
• Eosinophilic disorders, which are problems with one type of white blood cell.