1. A lower than normal number of red blood cells in the blood: "The results of the blood work done by the doctor indicated that Lora was suffering from anemia."

"The degree of anemia in Percy alarmed the doctor and so she prescribed medications."

2. A condition in which a person's blood does not have enough red corpuscles: "The severity of anemia is usually determined by how much the red blood cells have been decreased because when there is inadequate hemoglobin (iron-containing pigments of the red blood cells), all parts of the body receive less oxygen and have less energy than is normally needed to function properly."

A severe form of anemia, found mostly in older adults, that results from the body's inability to absorb vitamin B12.

Symptoms include weakness, breathing difficulties, and weight loss.

Patients who have this disorder do not produce the substance in the stomach that allows the body to absorb vitamin B12. This substance is called intrinsic factor (IF).

Pernicious anemia is characterized by the presence in the blood of large, immature, nucleated cells (megaloblasts) that are forerunners of red blood cells. (Red blood cells, when mature, have no nucleus). It is thus a type of megaloblastic anemia.

1. A chronic inherited anemia that occurs primarily in individuals of African, Mediterranean, or southwest Asian ancestry who are homozygous for the gene controlling hemoglobin S and that is characterized especially by episodic blocking of small blood vessels by sickle cells.
2. A chronic hereditary form of anemia that occurs mainly in people of African descent.

It is caused by a gene inherited from both parents.

A type of anemia, often hereditary in origin, characterized by the presence of spherocytes in the blood, a condition in which the concentration of hemoglobin in the circulating blood is below normal.

Symptoms include jaundice, splenomegaly, and fragility of the red blood cells.

Such a condition is caused by a deficient number of erythrocytes (red blood cells), an abnormally low level of hemoglobin in the individual cells, or both of these conditions simultaneously.

Regardless of the cause, all types of anemia cause similar signs and symptoms because of the blood's reduced capacity to carry oxygen and these symptoms include pallor of the skin and mucous membranes, weakness, dizziness, easy fatigability, and drowsiness.

Severe cases show difficulty in breathing, heart abnormalities, and digestive complaints.