What is transferrin and what are its normal levels?

Transferrin, hemoglobin and ferritin are key proteins in the diagnosis of anemia. Their concentrations are determined by laboratory tests.

Last update: June 09, 2022

Iron is an essential element in the human body for the formation of hemoglobin and the transport of oxygen. It moves through the bloodstream by various proteins, including transferrin. Are you interested in knowing what this molecule is like and what its normal levels are?

Transferrin is actively involved in iron metabolism. It is a protein whose function is to fix and transport iron in the bloodwhich is why it is also called iron binding protein. In addition, it is capable of transporting other metals in the body, such as manganese, copper, gallium and titanium.

Transferrin levels can be determined through laboratory blood tests. Its concentration may vary depending on the age, sex and general condition of the patient. It is very useful to identify alterations in red blood cells.

What is transferrin used for in the human body?

Transferrin is a glycoprotein produced primarily in the liver. It has an average half-life in the blood of 8 to 10 days, according to studies. Its function is to take the iron that is absorbed in the intestine and the iron that is obtained from the destruction of old red blood cells, to transport it in the blood.

Iron can be found in two forms: ferric (Fe3+) and ferrous (Fe2+). Each transferrin molecule is capable of capturing 2 iron ions in the ferric state.

In this way, it is called apotransferrin to the protein that does not have iron, monoferric transferrin when it has only one iron atom and diferric when you have 2.

Under normal conditions, only one-third of available transferrin is used for iron transport. If the body uses all of the available transferrin, it is called saturated transferrin. In this situation, the iron will not be able to be captured anymore and will accumulate in the liver.

Research suggests that of all the iron carried by transferrin, between 70% and 90% is taken up by the bone marrow to produce hemoglobin. In this way, the rest will be used to make enzymes and coordinate various metabolic reactions.

Older red blood cells break down and release iron, which is taken up by transferrin to carry on to another phase of metabolism.

How are blood transferrin levels measured?

Transferrin levels can be determined directly or indirectly. In this sense, the direct method identifies the exact concentration of this molecule from a blood sample. The indirect method is also called total iron binding capacity (CTFH).

CTFH measures the amount of iron-binding proteins, including transferrin. This test is usually cheaper and simpler, so it is more used by some specialists. Both methods are used to calculate the amount of circulating iron, so in the face of iron deficiency, we will see an elevation of transferrin and CTFH.

This assessment should be performed with the patient fasting for 8 to 12 hours.. In addition, levels are often ordered along with a complete hematology, blood chemistry, iron levels, and ferritin concentration.



Normal values

  • Men: 215 to 360 milligrams per deciliter (mg/dl).
  • Women: 250 to 370 milligrams per deciliter (mg/dl).
  • Kids: 200 to 350 milligrams per deciliter (mg/dl).

On the other hand, normal levels of CTFH vary between 250 and 350 micrograms per deciliter (µg/dl). The result changes depending on the sex, age and health status of the person. In addition, each laboratory offers its own criteria for normality and standardization.

high transferrin

In most cases, transferrin concentration is used to differentiate microcytic anemias. In this type of anemia, the red blood cells are smaller than normal.

Transferrin is elevated when values ​​above 360 ​​mg/dl in men and 370 mg/dl in women are obtained. Studies affirm that the most common cause of high transferrin is iron deficiency anemia or iron deficiency. Other causes include the following:

  • Pregnancy.
  • Polycythemia.
  • oral contraceptives
  • Estrogen hormone therapy.

low transferrin

We speak of low transferrin or hypotransferrinemia when this protein in the blood is below 215 mg/dl in men and 250 mg/dl in women. Among the causes of this phenomenon are the following:

  • Thalassemia.
  • Malnutrition.
  • sickle cell disease
  • Kidney diseases.
  • Sideroblastic anemia.
  • Extensive burns.
  • recurrent infections.
  • Liver disorders, such as cirrhosis.
  • Anemia typical of chronic diseases, such as cancer.
  • Use of medications, such as chloramphenicol and glucocorticoids.


What is the transferrin saturation index?

Transferrin is capable of binding 2 iron ions. However, most of these molecules are not usually fully occupied. In this sense, the transferrin saturation index evaluates the percentage of these proteins that are occupied by iron.

Under normal conditions, the value corresponds to 20-50% of total transferrin. However, in iron deficiency anemia, it increases, since there is not enough iron to be carried by transferrin.

The measurement of the parameters associated with transferrin is done by means of a laboratory test.

Is it possible to normalize the levels?

Transferrin levels in the blood depend directly on the concentration of iron. and the state of the red blood cells. In most cases, low levels are due to a lack of the mineral, so it is recommended to increase its consumption.

This can be achieved by increasing your intake of the following foods:

  • Eggs.
  • Red meat and liver.
  • Lentils and chickpeas.
  • Fish and shellfish.
  • Spinach and peaches.

If transferrin levels are decreased, it is necessary to solve the underlying cause so that these return to normal. The assessment must be carried out by health professionals, since they are the only ones trained to identify and treat these diseases.

A key protein in iron metabolism

Transferrin is an essential molecule for the transport of iron in the body. Its deficiency is related to different types of anemia, such as thalassemia, sickle cell disease and anemia of chronic diseases. On the other hand, excess is associated with iron deficiency, pregnancy and the use of contraceptives.

You might be interested…