Iron absorption is greater when there is an increased demand for iron, as for example during pregnancy.
The absorbed iron is transported as plasma ferritin and stored in liver, spleen, bone marrow and kidney. When red cells are broken down, the liberated iron is reutilized in the formation of new red cells.
The total daily iron loss of an adult is probably 1 mg and about 2 mg in menstruating women. Major routes of iron loss are:
- Through hemorrhages, that is wherever blood is lost, iron is lost, the causes of which may be physiological (e.g. menstruation, childbirth) or pathological (e.g. hookworms, malaria, hemorrhoids, peptic ulcer)
- Basal losses, such as excretion through urine, sweat and bile and desquamated surface cells.
- The recent widespread use of IUDs in the family planning programme is an additional cause of iron loss.
- Hormonal contraceptives on the other hand decrease menstrual blood loss by about 50 percent.
Iron is mostly absorbed from duodenum and upper small intestine in the ferrous state, according to body needs.
The rate of iron absorption is increased by many factors like iron reserves of the individual, the presence of inhibitors (e.g. phosphates) and promoters (e.g. ascorbic acid) of iron absorption and disorders of duodenum and jejunum.
Iron absorption is greater when there is an increased demand for iron, as for example during pregnancy.
The absorbed iron is transported as plasma ferritin and stored in liver, spleen, bone marrow and kidney. When red cells are broken down, the liberated iron is reutilized in the formation of new red cells.
Most of the iron is found in the red blood cells, where it forms part of that very complex protein known as hemoglobin. This is the red substance that gives color to the blood. It carries the oxygen to the tissues and keeps us alive.
Everyone knows that iron rusts when it is exposed to the air. Rusting is even more rapid when the air is damp. This chemical reaction is known as oxidation. A molecule of iron attaches itself to a molecule of oxygen from the air, forming iron oxide. This is exactly what happens when the red blood cells pass through the lungs. The air within the lungs is warm and damp, and the iron in the red cells actually rusts as it passes through the lung. All this happens with split second timing. From there the cells are carried by the blood stream to the heart, and then pumped to all the distant parts of the body, always carrying their load of oxygen.
Thus we see that iron is very important to the well being of all parts of the body. Most of the iron from the worn out cells is not discarded, but is separated from the hemoglobin in the liver and spleen and used over and over again. However a certain amount of iron may be lost from the body for various reasons such as bleeding hemorrhoids, injuries, menstruation, hookworm infestation or stomach ulcers.
Sometimes the level of the iron in the body may be lowered, owing to chronic blood loss or more probably to a poor diet. Iron may not be properly absorbed because the stomach is not producing sufficient hydrochloric acid. Sometimes this occurs during pregnancy.
Iron deficiency causes secondary anemia. The hemoglobin content of the red cells is diminished. The size and volume of the red cells are below average. There is normoblastic hyperplasia in the red bone marrow. Iron deficiency anemia occurs in children and adults due to severe blood loss.
Deficiency symptoms of iron
The patient usually complains of weakness, easy fatigue, and irritability. Other symptoms include heartburn, flatulence, vague abdominal pains, soreness in the mouth, numbness and tingling in the extremities, and palpitation of the heart. The skin and mucous membranes are pale, the nails are often brittle, and there are fissures or sores at the corners of the mouth.
Three stages of iron deficiency have been described:
- First stage is characterized by decreased storage of iron without any other detectable abnormalities.
- An intermediate stage of latent iron deficiency that is iron stores are exhausted, but anemia has not occurred as yet. Its recognition depends upon measurement of serum ferritin levels. This stage is the most prevalent stage in India.
- The third stage is that of overt iron deficiency when there is a decrease in the concentration of circulating hemoglobin due to impaired hemoglobin synthesis.
The end result of iron deficiency is nutritional anemia, which is not a disease. It is rather a syndrome caused by malnutrition. Besides anemia there may be other functional disturbances such as impaired cell mediated immunity, reduced resistance to infection, increased morbidity and mortality and diminished work performance.