Some common information about Lab Test Transferrin Saturation

Serum Transferrin Saturation is also known as Transferrin Saturation or transferrin.

Serum Transferrin Saturation lab test is frequently performed along with other related tests including Iron Tests, Serum Iron, Ferritin, Zinc Protoporphyrin, Complete Blood Count, Hemoglobin, Hematocrit, Reticulocyte Count, Soluble Transferrin Receptor.

Transferrin is a protein made by the liver. It is the main protein in the blood that binds to the iron absorbed from food and transports it throughout the body. Transferrin saturation is a calculation representing the percentage of this transferrin that is saturated with iron.

In healthy people, approximately one-third of the transferrin is saturated with iron. This leaves two-thirds as a reserve for binding extra transferrin should it be required.

Transferrin saturation is calculated from the measured amounts of transferrin and iron in your blood. These tests are can be measured with Iron and Ferritin to learn more about your body's iron stores if a doctor suspects you have too little or too much iron in your body.

In known cases of iron deficiency, the amount of transferrin saturation is an extremely good indicator of the amount of iron depletion in the body. Transferrin saturation in particular, is used to check for chronic iron overload, for example with excessive intake or a genetic disease called hemochromatosis.

High transferrin saturation levels
A high transferrin saturation results indicates you have too much iron in your body. In iron overload, the transferrin saturation is usually increased from around 30% to over 90%. Potential causes include excessive intake, possibly from iron supplements or multivitamins.

In some instances, it could also indicate genetic condition called hemochromatosis. This is an inherited disease in which the body absorbs too much iron, even on a normal diet. This disorder is most common in people from northern europe and is one of the more common genetic disorders.

Symptoms of iron overload include:

  • Joint pain
  • Fatigue
  • Weakness and lack of energy
  • Weight loss
  • Abdominal pain
  • Loss of sex drive
  • Loss of body hair

Treatments to reduce levels of iron are available, but the disease must be investigated and treated by a doctor.

Low transferrin saturation levels
Low transferrin saturation indicates you are likely to be suffering from iron deficiency. In iron deficiency, iron is low and fewer transferrin binding sites are used to the saturation of these binding sites is low.

Causes of iron deficiency can include:

  • Insufficient dietary iron intake
  • Inadequate iron absorption in the stomach
  • Increased need for iron, for example, during pregnancy
  • Any condition that causes chronic blood loss, for example heavy periods in menstruating women.

Treatment for iron deficiency anaemia usually involves taking iron supplements and changing your diet as well as treating any underlying cause. Foods rich in iron include red meat, pork, poultry and seafood.

The body is less able to absorb the iron found in plant based foods such as spinach, lentils, beans, and so supplementation is often required for vegetarian and vegan diets.

The transferrin saturation is calculated with the formula below.

(Serum iron level X 100) / total iron-binding capacity

Transferrin saturations of less than 20% indicate iron deficiency, while transferrin saturations of more than 50% suggest iron overload.

Iron tests frequently performed together to diagnose iron deficiency or overload include serum iron, ferritin, IBC, and transferrin levels.


  • The most common indication for obtaining a transferrin saturation level is to determine a patient’s iron status, either deficiency or overload.
  • The IBC value and transferrin saturation are best interpreted in the context of additional iron studies (typically, serum iron, ferritin, transferrin) and in the clinical context of the patient’s baseline health state.
  • After iron repletion, the IBC value may be redrawn with other iron tests to assess therapy.
  • The IBC is a useful test in determining the stage of iron deficiency. For example, the earliest markers of iron deficiency include ferritin, marrow iron, and IBC. These are followed by serum iron, percentage of transferrin saturation, and decreases in hemoglobin and hematocrit.
  • In pediatric populations with anemia, a transferrin saturation of less than 16% is diagnostic of iron deficiency anemia. It is limited by diurnal variation in serum iron levels.

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.