Serum Iron

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Serum Iron Test

To evaluate your body’s current store of iron

When this Serum Iron test is required

One or more iron tests may be requested when results from a routine FBC test are abnormal, such as a low haematocrit or haemoglobin, or when a doctor suspects that a person has iron deficiency due to the presence of signs and symptoms such as: Chronic fatigue/tiredness Shortness of breath and dizziness Weakness Headaches Leg pains Noticeable heartbeats (palpitations) If the anaemia is severe, angina (chest pain)Tests for iron, ferritin, transferrin saturation, and a transferrin or TIBC may be requested when a doctor suspects that a person may have a chronic iron overload. In the absence of a history of multiple transfusions, the most common cause of iron overload is a genetic condition called hereditary haemochromatosis. HFE genetic testing (see below) may be requested to help confirm a diagnosis of hereditary haemochromatosis and sometimes when a person has a family history of haemochromatosis. The signs and symptoms of iron overload are as follows: Unexplained joint and muscle pain Fatigue, weakness Abdominal pain Loss of sex drive, impotence, infertility or loss of menstrual periods Signs of liver disease, diabetes and / or heart problems Heart failure, liver failureWhen a child is suspected to have ingested iron tablets, a serum iron test is requested to detect and help assess the severity of the poisoning. A number of other tests may be requested together with iron tests to help the doctor determine the cause of iron deficiency and/or overload.The following tests can be used to help recognise problems with iron status. Haemoglobin and Haematocrit – These tests are performed as part of a Full Blood Count (FBC). A low value for either test indicates that a person has anaemia. Iron deficiency is a very common cause of anaemia. The average size of red cells (Mean Cell Volume or MCV) and the average amount of haemoglobin in red cells (Mean Cell Haemoglobin or MCH) are also measured in an FBC. In iron deficiency, insufficient haemoglobin is made, causing the red blood cells to be smaller and paler than normal. Both MCV and MCH are low. Blood film/picture- this test looks at the size and shape of red blood cells under a microscope. This helps to differentiate iron deficiency anaemia from other different types of anaemias. HFE gene test – Haemochromatosis is a genetic disease in Caucasians that causes the body to absorb too much iron. It is usually due to an inherited abnormality in a specific gene, called the HFE gene that affects the amount of iron absorbed from the gut. In people who have two copies of the abnormal gene too much iron can be absorbed and excess iron is deposited in many different organs, where it can cause damage and organ failure. The HFE gene test determines whether a person has the mutations that cause the disease. The most common mutation is called C282Y. Not everyone with this genetic mutation will develop haemochromatosis. Zinc Protoporphyrin (ZPP) – Protoporphyrin is the precursor to the part of haemoglobin (haem) that contains iron. If there is not enough iron, another metal, such as zinc, will attach to the protoporphyrin instead. The amount of zinc protoporphyrin in red cells is increased in iron deficiency. Sometimes ZPP (and its ratio to haem levels) is used as an early indicator of iron deficiency in children. However, the test is not specific for iron deficiency, and elevated values must be confirmed by other tests. The test is therefore rarely used in the UK, but still has a role in developing countries. Additional procedures such as testing the stool for blood (faecal occult blood [FOB] or faecal immunochemical test [FIT]), or endoscopy and colonoscopy may be used to find the cause of anaemia in cases of chronic bleeding from gut. Pelvic ultrasound scans are also used in women to look for the cause of excess menstrual bleeding. Liver function tests- This panel of tests may help identify liver damage in iron over load conditions. Liver biopsy- If liver damage is suspected following iron overload, a sample of tissue from the liver is removed, using a thin needle. The sample is sent to a laboratory to be checked for the presence of iron as well as for evidence of liver damage, especially scarring or cirrhosis.

What the Serum Iron Test Detects

Iron is an essential nutrient. It is needed in small quantities to help form normal red blood cells (RBCs). 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. Low iron levels can lead to anaemia and the production of RBCs that are small (microcytic) and pale (hypochromic). Large quantities of iron can be toxic to the…Iron is an essential nutrient. It is needed in small quantities to help form normal red blood cells (RBCs). 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. Low iron levels can lead to anaemia and the production of RBCs that are small (microcytic) and pale (hypochromic). Large quantities of iron can be toxic to the body, and absorption of too much iron over time can lead to the accumulation of iron compounds in organs and tissues. This can damage organs such as the liver, joints, heart, and pancreas. Iron is normally absorbed from food in the small intestine and transported throughout the body bound to transferrin, a transport protein produced by the liver. About 70% of the iron transported is incorporated into the haemoglobin inside RBCs. Most of the rest is stored in the tissues as ferritin or haemosiderin. Small amounts of iron are used to produce other proteins such as myoglobin (the oxygen carrying protein in muscle), and some enzymes. Iron tests evaluate the amount of iron in the body by measuring several substances in the blood. These tests [namely transferrin or TIBC, ferritin-see in detail below] are often requested at the same time and the results considered together to help diagnose and/or monitor iron deficiency or iron overload. Iron deficiency may be seen with insufficient intake, inadequate absorption, or increased requirements, such as may be seen during pregnancy or with acute or chronic blood loss. Iron overload may be acute or chronic. Acute iron poisoning may occur, especially in children, with the ingestion of iron tablets. Chronic overload may be due to excessive intake, hereditary haemochromatosis, multiple blood transfusions or several other conditions. See MoreSee Less

Preparation for the Serum Iron Test

Your doctor may request that you fast for 12 hours prior to some iron blood tests. In this case, only water is permitted. You should not take any iron tablets for 24 hours before the test. Iron is absorbed rapidly from food or tablets, and can make your blood iron levels falsely high.

Sample Requirements

A blood sample taken from a vein in your arm

Additional Notes

Normal iron concentrations are maintained by a balance between the amount of iron taken into the body and the amount of iron lost. Normally, a small amount of iron is lost each day, so if too little iron is taken in, deficiency will eventually develop. Unless a person has a poor diet, there is usually enough iron to prevent iron deficiency and/or iron deficiency anaemia 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, long term usage of nonsteroidal anti-inflammatory drugs [NSAIDs] such as Ibuprofen or Aspirin) or women with heavy menstrual periods will lose more iron than normal and can develop iron deficiency. Iron from food is absorbed into the bloodstream in the small intestine. An intestinal disorder, such as celiac disease, which affects the intestine’s ability to absorb nutrients from digested food, can lead to iron deficiency anemia. Women who are pregnant or breast feeding supply iron to their baby and can develop iron deficiency if not enough extra iron is taken in. Children, especially during times of rapid growth, may need extra iron and can develop iron deficiency.Low serum iron can also occur in states where the body cannot use iron properly despite sufficient iron stores. In many chronic diseases, especially cancers, autoimmune diseases, and chronic infections (including AIDS), the body cannot properly use iron to make more red cells, and so an anaemia develops. This disorder is known as “functional iron deficiency” or “anaemia of chronic disease”. The blood tests in persons with this condition will normally show low levels of serum iron and transferrin but normal or even high ferritin levels.Samples for iron should be taken in the morning, before you have had any food to eat. You should not take any iron pills or tablets for 24 hours before the test. Iron is absorbed rapidly from food or pills, and can make your blood iron levels falsely high.Substances that can cause high iron levels include the contraceptive pill, oestrogen pills and preparations, iron supplements, heavy intake of alcoholic drinks, methyldopa, and chloramphenicol.Substances that can cause your iron level to be decreased include ACTH (a hormone), the drugs colchicine, desferrioxamine, methicillin, and testosterone.

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