Optimal Result: 27 - 159 µg/dL, 4.83 - 28.46 µmol/L, or 27.00 - 159.00 umol/L.

Iron - the basics:

- Iron is supplied by the diet. 

- As much as 70% of the iron in the body is found in the hemoglobin of the red blood cells (RBCs). 

- The other 30% is stored in the form of ferritin and hemosiderin (=iron-storage complex within cells, not widely available). 

- About 10% of the ingested iron is absorbed in the small intestine and transported to the plasma.

- Abnormal levels of iron are characteristic of many diseases, including iron-deficiency anemia and hemochromatosis (=Iron overload). 

Where is iron found in the body?

Most iron in the body is bound to red blood cells or stored in the spleen and cannot be directly tested. 

Iron is found in different parts of the body:

- In the blood. About 65% of all iron is in the blood. Iron in the blood is mostly bound to the transportation protein transferrin. 

- In muscles 

- In the liver (called ferritin) 

- In enzymes in the body. 

Iron and transferrin:

- After iron is absorbed in the small intestine and transported to the plasma, there the iron is bound to a globulin protein called transferrin and carried to the bone marrow for incorporation into hemoglobin.

- Transferrin exists in relation to the need for iron. When iron stores are low, transferrin levels increase, whereas transferrin is low when there is too much iron.

- Usually about one-third of the transferrin is being used to transport iron. Because of this, the blood serum has considerable extra iron-binding capacity, which is the Unsaturated Iron Binding Capacity (UIBC). The TIBC equals UIBC plus the serum iron measurement. Some laboratories measure UIBC, some measure TIBC, and some measure transferrin. 

- The serum iron determination is a measurement of the quantity of iron bound to transferrin.

Why is iron so important?

- Iron is an essential element required for hemoglobin production. 

- The human body requires iron to perform many vital physiological functions. 

What is hemoglobin?

Hemoglobin oxygenates the blood. Without iron, red blood cells cannot reproduce in the body. 

How is iron absorbed in the body?

- The body takes in iron from the food you eat so it is important to have good sources of iron in your diet. Only about 10% of the iron you consume is absorbed. 

- The process of iron absorption is tightly regulated because your body does not have any biochemical ways of removing iron. Instead, iron is lost through processes such as bleeding, menstruation, and breast-feeding. Additionally, iron within the body is constantly being recycled and reused. 

What does a serum test do?

A serum iron test measures iron levels in the serum component of the blood. A serum iron test is ordered after abnormal results are found in a hemoglobin test or a complete blood count, or when you are showing symptoms of anemia. 

How is iron measured?

- Iron is often measured in micrograms per deciliter (mcg/dl), normal ranges for serum iron differ depending on an individual’s age and sex. 

- Child-bearing women have the highest requirements for iron because of the monthly loss of blood in their menstrual cycles. 

- If your results are abnormal, additional tests will determine whether iron is being stored in your liver, not being transported to the right places in your body, or what type of anemia you have.

What does it mean if your Iron result is too low?

Iron deficiency is a condition resulting from too little iron in the body. Iron deficiency can be the result of numerous and multiple causes. 

Possible Causes:

- Your diet may not contain enough iron-rich foods. Even a vitamin C deficiency affects the absorption of iron in the diet, and it’s possible that if you’re low in vitamin C, you won’t absorb enough iron from other foods.

- If you are a woman in the child-bearing years, then heavy menstrual periods could contribute to low iron levels. That’s because blood is exiting the body at high levels – and taking iron with it.

- Acute or chronic blood loss, including from ulcers or bleeding from the GI tract

- Anemia (iron-deficiency, sickle cell, vitamin B6 deficiency, vitamin B12 deficiency, vitamin C deficiency)

- Pregnancy

- Bone marrow conditions

- Infections

- Hypothyroidism

- Kwashiorkor (malnutrition)

- Associated with blood loss during surgery

Possible symptoms:

- premature births

- low birth weight babies

- delayed growth and development

- delayed normal infant activity and movement. 

- Lower IQs have been linked to iron deficiency occurring during critical periods of growth.

- Iron deficiency can result in poor memory or poor cognitive skills (mental function) and can result in poor performance in school, work, etc. 

Possible signs of iron deficiency:

A person who is iron deficient may also be anemic and as a result may have one or more symptoms of anemia. 

These can include:

- chronic fatigue

- Weakness

- Dizziness

- Headaches

- Depression

- sore tongue

- sensitivity to cold (low body temp)

- shortness of breath doing simple tasks (climbing stairs, walking short distances, doing housework)

- restless legs syndrome

- pica (the desire to chew ice or non-food items,)

- and loss of interest in work, recreation, relationships, and intimacy.

Most at risk for iron deficiency:

Women, children and the elderly are most at risk. African American and Hispanic women and their young children are prone to iron deficiency, possibly because of diet or perhaps different hemoglobin needs. Men are rarely iron deficient; but when they are, it is generally due to blood loss from the digestive tract (sometimes indicating disease), diseases that affect iron absorption, and in some cases, alcohol abuse. Except for those who are strict vegetarians, men rarely have dietary iron deficiency.

Possible correlations to other markers:

You should also correlate your low iron levels to other biomarkers. 

A decreased serum iron level, elevated total iron-binding capacity (TIBC), and low transferrin saturation value are characteristic of iron-deficiency anemia.

Here are possible scenarios of correlation:



TIBC/ Transferrin



Saturation (%)


Iron Deficiency




Low Low

Chronic Illness



Low/Normal Low/Normal



- You can also look at RDW (=Red Cell Distribution Width) and MCV (=Mean Corpuscular Volume), if you have those measurements, to distinguish between different kinds of anemias. Refer to your RDW and MCV markers for more information. 

- Low zinc levels can also be associated with iron deficiency anemia. Zinc is the co-factor of several enzymes and plays a role in iron metabolism, so zinc deficiency is associated with IDA (=iron deficiency anemia). Refer to your zinc marker for more information.

What does it mean if your Iron result is too high?

Chronic iron overload or poisoning is called hemochromatosis or hemosiderosis. Excess iron is usually deposited in the brain, liver, and heart and causes severe dysfunction of these organs.

Massive blood transfusions also may cause elevated serum iron levels, although only transiently. Transfusions should be avoided before serum iron level determinations.

Possible causes:

High levels of iron in the serum are associated with too much iron, vitamin B6 or vitamin B12. 

Some specific causes of high iron might be: 

- anemia where the blood cells rupture, called hemolytic anemia

- iron overdose, where you have consumed more iron than what your body requires and can successfully deal with

- an overload of iron, where your body is not eliminating iron as it should

- liver health issues such as hemosiderosis, hemochromatosis, liver failure or hepatitis

- too many blood transfusions

- lead poisoning

- use of birth control pills

What can iron overload do to the body?

- Too much iron in vital organs, even in mild cases of iron overload, increases the risk for liver disease (cirrhosis, cancer), heart attack or heart failure, diabetes mellitus, osteoarthritis, osteoporosis, metabolic syndrome, hypothyroidism, hypogonadism, numerous symptoms and in some cases premature death. 

- Iron mismanagement resulting in overload can accelerate such neurodegenerative diseases as Alzheimer’s, early-onset Parkinson’s, Huntington’s, epilepsy and multiple sclerosis.

Possible treatment:

The treatment for iron overload is iron reduction therapy. A person's hemoglobin is key in the physician's decision of iron reduction therapy. If the patient's hemoglobin level is sufficient to tolerate blood removal, the doctor can provide either an order for therapeutic phlebotomies or can recommend that a patient routinely donate blood.

Possible correlations to other markers:

You should also correlate your high iron levels to other biomarkers. 

Acute iron poisoning due to accidental or intentional overdose is characterized by a serum iron level that exceeds the total iron binding capacity (TIBC).

Here are possible scenarios of correlation:



TIBC/ Transferrin



Saturation (%)


Hemocromatosis/ Hemosiderosis

High Low Low High High

Hemolytic Anemia




High High

Sideroblastic Anemia




High High

Iron Poisoning

High Normal Low High Normal
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