Final answer:
Celiac disease causes malabsorption, gastrectomy reduces iron absorption, and chronic blood loss depletes iron stores.
Step-by-step explanation:
Celiac disease causes malabsorption, gastrectomy reduces iron absorption, and chronic blood loss depletes iron stores. Iron deficiency occurs as a result of malabsorption from the gastrointestinal tract, impaired absorption in patients who have total removal of the stomach or a removal of a considerable amount of the intestine, and pathological blood loss from various sources such as bleeding piles, peptic ulcer, and gastrointestinal tract cancer.