What is the reason for the lack of blood?

A lack of blood is called anemia. It occurs because there is not enough blood produced or because of blood loss. Poor blood formation is associated with poor nutrition (lack of iron), with the presence of parasites in the body, with an excessive need for iron (for example, in pregnant women, in children). Blood loss can be acute or chronic. Acute occurs due to injury or due to damage to internal organs (for example, acute bleeding from the veins of the esophagus). Chronic blood loss is usually associated with small ulcers, such as in the stomach, that gradually bleed.