Red blood cells, or erythrocytes, make up the majority of your blood. They carry oxygen to cells throughout the body and remove carbon dioxide. Red blood cells are produced in the bone marrow, the soft tissue at the center of our bones. A healthy adult produced almost 2.4 million new red blood cells per second. They generally live between 100 and 120 days before being recycled by the body.
Blood disorders involving red blood cells manifest in two ways: a high red-blood cell count or a low red-blood cell count.
There are many conditions that can affect the number of red blood cells your body produces and how long they survive. Too many red blood cells make your blood thicker than usual, which slows down its flow and makes it difficult for your organs to get enough oxygen. It can be caused by:
Excess production of the proteins that stimulate red blood cell production (a common side effect of kidney disease)
Problems with bone marrow
When your blood contains too few red blood cells, you have anemia. There are many types of anemia, based on the cause of your low red blood cell count. Causes of anemia can include:
Lack of iron from low iron intake or blood loss (common in menstruating women)
Chronic disease, including kidney disease
Vitamin B12 deficiency
Bone marrow disorders
Inherited conditions, including Thalassemia and sickle cell anemia
Anemia of chronic disease
Pernicious anemia (Vitamin B12 deficiency)
Autoimmune hemolytic anemia
White blood cells, or leukocytes, are the body’s main defense against disease or infection. White blood cells are produced in the bone marrow, the soft tissue at the center of every bone, and live for about 3-4 days. In a healthy adult, they make up only about 1 percent of your total blood supply.
Blood disorders involving white blood cells manifest in two ways: a high white-blood cell count or a low white-blood cell count.
An increased white blood cell count is usually an indicator of illness, as your body works fights off infection. However, a white blood cell count that remains high can indicate a disease of the bone marrow or an immune system disorder that affects overall white blood cell production.
Increased white blood cell counts are a common symptom of cancers such as acute lymphocytic leukemia (ALL) and acute myelogenous leukemia (AML), but they can also be caused by:
Drug interactions (especially corticosteroids)
Polycythemia vera (too many red blood cells)
Similarly, a low white blood cell count places you at increased risk of infection or illness, because your body’s natural defenses are lowered. In addition to various forms of leukemia, low white blood cell counts can be caused by:
Cancer treatment, including chemotherapy and radiation therapy
Medications such as antibiotics and diaretics
Platelets, or thrombocytes, are blood cells that promote clotting, so that when you are wounded, your body can stop blood loss. Platelets make up between 5 and 10 percent of your total blood flow.
Blood disorders involving platelets manifest in two ways: a high platelet count or a low platelet count.
When your platelet count is too high, your blood can clot inside your body, leading to potentially life-threatening conditions including pulmonary embolism. There are a number of conditions that lead to increased platelet counts, including:
Acute blood loss
Chronic kidney disease
Disorders of the bone marrow
Low platelet count can be the result of an inherited disorder such as hemophilia, a side effect of certain medications, or a sign of an immune system disorder.