• Red blood cells and haemoglobin, the molecule inside them that makes them red, carry oxygen from the lungs around the body.
• To make haemoglobin, your body needs iron.
• 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 medical team may request iron studies if you have symptoms of having too little or too much iron. 

Your body needs iron for daily activities, growth and development. It uses iron to make haemoglobin in red blood cells. Red blood cells carry oxygen through the bloodstream from the lungs and release it to where it is needed in the body. 

Our bodies cannot make iron. It must be absorbed from our diet or from supplements. The amount of iron we absorb is decided by our body's needs. We normally use just a little bit of iron each day and we don’t have a way of getting rid of excess iron. Instead, the body closely controls iron levels by regulating how much iron is absorbed from our food.

If your iron levels are too low, your body will not be able to make enough haemoglobin to function properly. This condition is known as iron-deficiency anaemia. It is also possible to have too much iron, which is known as iron overload, and it may be caused by an inherited condition called haemochromatosis.

How iron is taken up and used

• Iron is absorbed from your food into the bloodstream through your small intestine. Once the iron enters the blood, it sticks to a protein called transferrin. Transferrin transports it to various tissues throughout the body.
• Iron is stored in a protein called ferritin. This is found all over your body but mainly in the liver. Ferritin releases iron as it is needed when your body detects low iron levels in your blood.  
• Entering the bloodstream, iron once again sticks to transferrin, and it travels to the bone marrow where new blood cells are made.
• Here it is taken up by newly forming red blood cells which have transferrin receptors on their surface.  Entering through the receptor it moves into the cell where the iron is separated from the transferrin.

Since red blood cells live for an average of about 120 days, the body needs a constant supply of iron to maintain haemoglobin levels. Dying red blood cells are recycled and old haemoglobin is broken down to rebuild iron supplies.

The iron studies panel is made up of several tests. Usually, they include: 

• Ferritin
• Seum iron
• Transferrin
• Transferrin saturation or Total iron binding capacity (TIBC)

The tests included in the iron studies panel may vary slightly depending on the laboratory 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. 

The tests used to assess your iron status include:

Ferritin – iron storage

When the iron stored in ferritin is released into the blood stream it is transported to the bone marrow where it is incorporated into new red blood cells.  As this happens, a small amount of ferritin is released from the cells and circulates in the blood.  Measuring the level of ferritin in your blood is a good indication of the amount of iron stored in your body.

Transferrin and total iron binding capacity (TIBC) - iron transportation

Your body makes transferrin in relation to your need for iron. When iron stores are low, transferrin levels increase. When there is too much iron in the body transferrin levels are low. 

Transferrin and TIBC are different tests that measure the same thing — the amount of iron that can be transported in your blood. TIBC is an older test that is no longer routinely used by most labs.

Serum iron concentration

The amount of iron that circulates in the blood varies markedly throughout the day.

Measurement of iron alone is rarely helpful and needs to be combined with the results of other iron study tests to provide accurate results. It is most useful in calculating transferrin saturation.

Transferrin saturation
The serum iron result and the transferrin results can be combined to calculate the transferrin saturation (TFSAT). The TFSAT shows what percentage of all the transferrin in the blood contains iron. The TFSAT level is usually between 15 and 45 per cent. In iron deficiency, the TFSAT level will be low, and if there is too much iron in the body the TFSAT will be high.

If a problem with iron is suspected, your medical team may first request a full blood count (FBC), which gives information on the number, size and shape of your red blood cells and how much haemoglobin is in the blood. If the FBC suggests iron deficiency, iron studies will be requested as the next investigation.

Too little iron (iron deficiency)

Causes of iron deficiency include:

• Not enough iron in your diet, for example, vegetarian and vegan diets.
• Pregnancy, because you need more iron to support the growing baby.
• An inability to absorb iron, for example if you have had bowel or stomach surgery or have Inflammatory Bowel Disease (IBD).
• Chronic bleeding, for example, iron loss from a bleeding stomach ulcer.

Iron deficiency comes on gradually. When the rate of iron loss is more than the amount of iron you absorb from your diet the first thing that occurs is that iron stores are used up. At this stage, ferritin will be low, but iron and transferrin may be normal and there is no anaemia.

As iron deficiency worsens, blood iron levels fall, TIBC and transferrin rise, and red blood cells may start to become small and pale, but there are still enough red blood cells.

With longstanding iron deficiency, iron stores are used up and there is insufficient iron to make enough haemoglobin — a condition known as iron deficiency anaemia. The red blood cells will be smaller than usual (microcytic) and paler than normal (hypochromic).

Too much iron (iron overload, haemochromatosis)

In iron overload, caused by haemochromatosis, iron builds up in the organs and can result in liver disease, diabetes, arthritis and pituitary gland disorders. See HFE mutations for more information.

Another cause of excess iron are regular blood transfusions. The iron from the transfused red blood cells can build up in the body and cause similar symptoms to haemochromatosis.

Sample

Blood.

Any preparation?
Do not take iron supplements or food before having a blood sample collected for iron studies. 

Reading your test report
Your results will be presented along with those of your other tests on the same form.  You will see separate columns or lines for each of the tests that make up the iron studies panel.

Reference intervals 

Your results will be compared to reference intervals (sometimes called a normal range). 

• Reference intervals are the range of results expected in most healthy people of the same age and sex. 
• Your results may be flagged high or low if they sit outside this range.
• Many reference intervals vary between labs so only those that are the same across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. Blood test results must be interpreted with an understanding of your own particular symptoms and clinical situation.  For this reason, your results are best interpreted by your own doctor.

The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

If you are diagnosed with iron deficiency you may need to take iron supplements. Alternatively, your medical team may suggest you have an iron infusion. In very severe iron deficiency due to bleeding, you may require a blood transfusion. It is not recommended to take iron supplements unless advised to do so by your doctor.