Iron studies are requested in two main situations; the investigation of the cause of anaemia and when iron excess is suspected.
This term refers to the presence of too few red blood cells, which are needed to carry oxygen to the body. Many conditions can cause anaemia, but iron deficiency is one of the most common. Normal iron levels are maintained by a balance between the amount of iron taken into the body and the amount of iron lost. Normally, we lose a small amount of iron each day, so if we take in too little iron, deficiency could develop. Unless a person follows a very poor diet, however, there is usually enough iron to prevent iron deficiency in healthy people.
In certain situations there is an increased need for iron. Persons with chronic bleeding from the gut (usually from ulcers or tumours), or women with heavy menstrual periods will lose more iron than normal and often develop iron deficiency. Women who are pregnant or breast feeding lose iron to their baby, and can develop iron deficiency if not enough extra iron is taken. Children, especially during times of rapid growth, need extra iron and can develop iron deficiency.
Anaemia can also occur in states where the body cannot use iron properly. In many chronic diseases, especially in cancers, autoimmune diseases, and with chronic infections (including AIDS), the body cannot use iron properly to make red cells. As a result, production of decreases, serum iron is low (because little iron is being absorbed from the gut), and ferritin (the storage form of iron) increases.
Iron deficiency occurs with varying degrees of severity. The mildest stage is iron depletion, which means the amount of functioning iron in your body is all right, but the body does not have any extra iron stores. Serum iron is usually normal in this stage. As iron deficiency worsens, iron-deficient erythropoiesis (formation of red blood cells) develops; all of your stored iron is gone and your body begins to produce more transferrin to increase iron transport. As this stage progresses, red cells are produced in normal numbers but they have less haemoglobin than normal (microcytic and hypochromic red cells).
In iron-deficiency anaemia, the most severe form of iron deficiency, the number of red cells produced is low, anaemia develops, serum iron is low, ferritin is low, and transferrin and TIBC are high.
Too much iron can lead to damage to a number of organs, including the heart, liver, pancreas (where insulin is made) and most commonly. The most common cause of iron excess is an inherited disease called haemochromatosis. In this disease, the body absorbs more iron than it needs from the gut, and the excess iron gradually accumulates, causing organ damage over many years. The disease is inherited when you get one copy of an abnormal form of the HFE gene from each of your parents (who show no evidence of the disease).
Many people who have haemochromatosis will have no symptoms for their whole life, while others start to develop symptoms such as joint pain, abdominal pain, and weakness in their 20’s or 30’s. Heavy alcohol consumption seems to increase the amount of iron absorbed, while women are somewhat protected because they lose iron every month with their menstrual period.
There is now a test to detect the abnormal form of the gene; this can be used if you have unexplained high iron levels or if you have a family history of haemochromatosis.
Iron poisoning occurs if a large amount of iron is taken all at once. While this is rare, it most commonly occurs in children who get hold of their mother's iron supplements or a bottle of vitamins with iron. If severe enough, iron poisoning can cause death, so it is a good idea to keep all iron supplements well out of the reach of children.