Keeping blood iron values under control is also important for those who do not suffer from anaemia or iron deficiency. In this in-depth article, we will find out what the normal values of iron in blood tests are and which tests are useful for keeping blood iron levels, i.e., the balance and metabolism of iron in our body, under control.
What are the normal values of iron in the blood?
Iron is an essential nutrient for the body and plays an important role in the formation of haemoglobin, myoglobin and various biochemical and metabolic processes in the body. Both a deficiency and an excess of iron can lead to imbalances, therefore, it is important to keep the amount of iron in the body under control.
Iron always circulates in the blood bound to proteins that prevent it from binding with other molecules. Free iron in the blood could react with other substances and cause damage to the body. Therefore, when measuring iron values in the body, free iron is not measured in the form of atoms or, to be more precise, ions, but rather iron bound to the specific proteins that regulate its transport and storage.
Iron in the blood is measured by three values:
serum iron, which measures the amount of circulating iron bound to transferrin;
transferrin levels, which measures the amount of this protein that transports iron to the organs and tissues where erythropoiesis occurs, i.e., the synthesis of red blood cells;
ferritin levels, which measures the amount of this protein that regulates the deposit and storage of iron in the liver, muscles and bone marrow.
These laboratory tests are usually performed when iron deficiency anaemia (sideropenic anaemia) is suspected or when there is a condition of asthenia and general malaise characterised by the typical symptoms of iron deficiency, such as paleness of the skin and mucous membranes, headache, increased irritability, breathing and sleep disturbances. The measurement of serum iron, transferrin and ferritin levels also serves to monitor the development of certain blood disorders.
Iron blood analysis: the values
The reference values given below may vary slightly from one laboratory to another, depending on the reference population or method of analysis used. For the reference intervals, it is recommended to consider those specified in the report. Consult your doctor for the correct interpretation of the test results.
This value is usually measured together with serum iron and is useful for understanding the maximum potential amount of transferrin to bind iron. When the result is less than or equal to the lower limit of the reference range, it means that the transport capacity of the iron is not optimal. Low TIBC values associated with high amounts of circulating iron mean that the body is no longer able to keep the iron in balance and the circulating ion can become toxic.
The TIBC values are: 255-450 μg/dL
Transferrin saturation
This is a value (expressed as a percentage) calculated by dividing the serum iron by the TIBC. In adults, the optimal situation is when transferrin saturation is between 20 and 50%. In children, transferrin saturation must be over 16%.
Transferrin reserve capacity (UIBC)
This value indicates the portion of unsaturated transferrin with iron. The measurement can be carried out by direct examination or the UIBC can be calculated by subtracting the TIBC value from that of serum iron.
UIBC = TIBC – serum iron.
Haemoglobin (Hb) values
Although they do not give a direct indication of the amount of iron in the body, haemoglobin values are usually taken into account, along with serum iron, transferrin and ferritin values, when iron deficiency anaemia is suspected.
The normal values of haemoglobin (Hb) are:
Men: 13.4 – 17.5 g/dL
Women: 12 – 15.5 g/dL
Pregnant women: 11 – 14 g/dL
The average haemoglobin values in children and adolescents are (depending on age and gender):
Birth: average 16.5 g/dL
First month: average 14.0 g/dL
2 months: average 11.5 g/dL
3-6 months: average 11.5 g/dL
From 6 months to 2 years: average 12.0 g/dL
2-6 years: average 12.5 g/dL
6-12 years: average 13.5 g/dL
12-18 year old girls: average 14.0 g/dL
12-18 year old boys: average 14.5 g/dL
Haematocrit
Together with the haemoglobin values, haematocrit, which represents the volume of blood (expressed as a percentage) occupied by red blood cells, is often measured.
