Lack of hemoglobin in the body causes
anaemia
The red blood cell contains iron in its hemoglobin, the protein that carries oxygen to the body's tissues from the lungs. Iron gives hemoglobin the ability to carry oxygen in the blood. People become iron deficient when they aren't getting enough iron in their diet. This means that the body can't make hemoglobin, so it makes fewer red blood cells. This is a condition called anaemia.