Our body needs iron absorbed from food. Transferrin is a protein mainly produced in the liver that binds iron (S-Fe) and carries it to tissues and cells all over the body. Transferrin carries approximately 80% of iron to bone marrow. From there, it is transported to haemoglobin in the red blood cells. The rest of the iron is stored in cells and tissues as ferritin (S-Ferrit) or hemosiderin (Hemsi).
Typically, approximately one third of measured transferrin carries iron. This is called transferrin saturation (fS-TrFeSat). If there is not enough iron in the body, the amount of iron bound to transferrin decreases. Similarly, if there is plenty of iron in the blood, the amount of bound iron increases.
Because red blood cells live for approximately 120 days, bone marrow has to continuously produce new red blood cells. If you do not get enough iron from food or in case of bleeding, for example, the amount of iron stored in the body decreases.In time, this leads to iron deficiency. Red blood cell production is decreased, and the new red blood cells are smaller and contain less haemoglobin. This leads to iron deficiency anaemia.
When should transferrin saturation be measured?
A transferrin saturation test is used when it is suspected that there is too much or too little iron in the body. It is also used to investigate anaemia or iron storage disease.
A transferrin saturation test is recommended in case of the following symptoms:
- Low haemoglobin (Hb)
- Small red blood cells (low MCV)
What does a transferrin saturation test measure?
The test is used to measure the share of transferrin saturated with iron. It reflects the iron balance of the body: If there is too little iron in the body, the transferrin binding sites are used less and transferrin saturation is low. Similarly, when there is an excess of iron in the body, transferrin saturation is high.
How to interpret the transferrin saturation test result?
Normally, the result is: Reference values: Transferrin saturation: 15–50%
Read more about defining reference values.
Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.
What can cause elevated transferrin saturation values?
Elevated transferrin values can occur, for example, in the following situations:
- Use of iron preparations
- Use of contraceptive pills
- Iron deficiency anaemia (high transferrin but low transferrin saturation)
What can cause decreased transferrin saturation values?
Low transferrin values occur, for example, in the following situations:
- Chronic liver disease
- Malignant tumours
The most typical additional tests for transferrin:
Complete blood count (CBC), shows the number of red and white blood cells, number of platelets and cell type (3696 B-TVK)
Transferrin receptor, soluble, carries iron into cells and tissues (1949 S -TfR)
Ferritin indicates the status of the iron reserves of the body (1395 S-Ferrit)
All cells in the body need iron (2566 fS-Fe)
SYNLAB test list: Transferrin (2756 fS-Transf), Transferrin saturation (4606 fS-TrFeSat, fS-Fe, fS-Transf) https://www2.synlab.fi/laboratoriokasikirja/tutkimuskuvaukset/transferriini/
Lab Tests online: TIBC, UIBC and Transferrin https://labtestsonline.org.uk/tests/tibc-uibc-and-transferrin
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