Iron Studies is the name of a group or panel of blood tests that collectively looks at how much iron is in your blood and body. Your doctor may request iron studies if you have symptoms of having too little or too much iron.
The iron studies panel is made up of several tests, most commonly:
-Transferrin saturation or
-Total iron binding capacity (TIBC)
The tests included in the iron studies panel may vary slightly depending on the lab doing the testing. Each test measures a different aspect of the storage and transportation of iron in the blood. By assessing each result, your doctor can build up a picture of your overall iron status.
What is being tested?
Iron is needed to help form adequate numbers of normal red blood cells, which carry oxygen throughout the body. Iron is a critical part of haemoglobin, the protein in red blood cells that binds oxygen in the lungs and releases it as blood travels to other parts of the body. Iron is also needed by other cells, especially muscle (which contains another oxygen binding protein called myoglobin). Low iron levels can lead to anaemia, in which the body does not have enough red blood cells. Other conditions can cause you to have too much iron in your blood.
Evaluation of iron status can include several tests that are not always run together. These include:
These tests are often requested together, and the relative changes in each can help your doctor determine the cause of an abnormal result in one or more of these tests.
Several other tests can also be used to help recognise problems with iron in the body.
How is it used?
Iron status may be evaluated by ordering one or more tests to determine the amount of iron in the blood, the capacity of the blood to transport iron, and the amount of iron in storage. They may also help differentiate various causes of anaemia.
When is it requested?
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 transferrin 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 joints 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.
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.
What does the result mean?
A summary of the changes in iron tests seen in various diseases of iron status is shown in the table below.
Iron deficiency refers to a decrease in the amount of iron stored in the body, while anaemia refers to a drop in the number of red blood cells (RBCs) and/or the amount of haemoglobin within the RBCs. It typically takes several weeks after iron stores are depleted for the level of haemoglobin and production of RBCs to be affected and for anaemia to develop. There usually are few symptoms early in iron deficiency, but as the condition worsens and blood levels of haemoglobin and RBCs decrease, then ongoing weakness and fatigue can develop.
As your iron continues to be depleted, you may have shortness of breath and dizziness. If the anaemia is severe, chest pain, headaches, and leg pains may occur. Children may develop learning (cognitive) disabilities. Besides the general symptoms of anaemia, there are certain symptoms that are characteristic of iron deficiency. These include pica (cravings for specific substances, such as licorice, chalk, dirt, or clay), a burning sensation in the tongue or a smooth tongue, sores at the corners of the mouth, and spoon-shaped finger- and toe-nails.
There are many different conditions that can cause anaemia other than iron deficiency. Some examples include B vitamin deficiency, cancer and genetic disorders such as sickle-cell disease and thalassaemia. However, iron deficiency is the most common cause, which is why iron tests are so frequently performed. If iron tests rule out iron deficiency, another source for the anaemia must be found. See the article on Anaemia for more on these.
Haem-iron is the easiest form of iron for the body to absorb. It is found in meats and eggs. Non-haem iron is found in a wide variety of plants and in iron supplements. Iron-rich sources include: green leafy vegetables, (such as spinach, collard greens and kale), wheat germ, whole grain breads and cereals, raisins, and molasses. If you have been diagnosed with iron deficiency anaemia or you are pregnant or breast feeding, vitamin pills or tablets may be needed to provide extra iron. Ask your doctor about the right supplement for you.
The people who typically need iron supplements are pregnant women and patients with documented iron deficiency. People should not take iron supplements before talking to their doctor as excess iron can cause chronic iron overload. An overdose of iron pills can be toxic, especially to children.