Evaluation of transferrin saturation
Why this test?
- To assess iron metabolism in detail (together with a test for iron in the serum and for the total iron-binding capacity of the serum - the combination of these tests allows you to calculate the percentage of saturation of transferrin with iron, that is, to determine how much iron the blood carries).
- This indicator most accurately characterizes iron metabolism.
- To assess the iron reserve in body.
- To determine whether anemia is caused by iron deficiency or other causes, such as chronic disease or vitamin B12 deficiency.
- With iron deficiency, its level in the serum falls, but the level of transferrin increases.
- To assess liver function.
In what cases is it prescribed?
- If any deviations are detected in the general blood test, analysis of hemoglobin, hematocrit, number of erythrocytes.
- If iron deficiency or excess iron in the body is suspected.
- In case of suspicion of an overload of the body with iron (hemochromatosis).
- Symptoms of hemochromatosis: joint and abdominal pain, weakness, fatigue, decreased sexual desire, heart rhythm disturbances.
- In case of suspicion of chronic liver disease or changes in intestinal absorption.
Normally, the body contains 4-5 g of iron, about 3-4 mg (0.1% of the total amount) circulates in the blood in combination with transferrin. As a rule, 1/3 of the binding centers of transferrin are filled with iron, the other 2/3 remain in reserve.
The degree of «filling» of transferrin with iron is reflected by such indicators as the total iron-binding capacity of the serum, the latent iron-binding capacity of the serum and the percentage of transferrin saturation. Iron saturation of transferrin is a calculated value - the ratio of serum iron concentration to the total iron-binding capacity of transferrin, expressed as a percentage. The percentage (fraction) of saturation is a better indicator of iron stores than the serum iron concentration.
Taking into account that 1 g of transferrin binds approximately 1.25 mg of iron, it is possible to determine the total amount of iron that can bind serum transferrin. Normally, the percentage of transferrin saturation with iron is approximately 20-55%. In iron-deficiency anemia, a decrease in the percentage of transferrin saturation with iron is observed.