Transferrin is a key marker in the evaluation of iron metabolism disorders.
Transferrin measurement—particularly as transferrin saturation—is significant in the workup of a patient with persistent fatigue, muscle weakness, and intermittent double vision, as these symptoms may be related to iron deficiency or iron overload.
Transferrin is the main iron transport protein in plasma.
In iron deficiency, transferrin levels are typically elevated, but transferrin saturation, the percentage of transferrin bound to iron, is reduced, usually below 16–20% indicating insufficient iron available for erythropoiesis and tissue function, which can manifest as fatigue and muscle weakness.
In iron overload disorders such as hereditary hemochromatosis, transferrin saturation is elevated (often >45–50%), and this can also present with nonspecific symptoms like fatigue and muscle weakness.
Transferrin is a blood plasma glycoprotein that serves as the primary iron transport protein in the body.
Transferrin binds to iron absorbed from the intestines or released from storage sites and transports it through the bloodstream to cells throughout the body, particularly to bone marrow for red blood cell production.
Transferrin helps maintain iron homeostasis and prevents free iron from causing oxidative damage
Molecular weight of approximately 80 kDa Can bind up to two Fe³⁺ (ferric iron) ions Synthesized primarily in the liver
The percentage of transferrin binding sites occupied by iron is an important diagnostic marker:
Normal range: typically 20-45%
Low saturation suggests iron deficiency
High saturation may indicate iron overload conditions
In Iron deficiency anemia transferrin levels increase as the body tries to capture more iron.
Transferrin levels may decrease in chronic disease.
Low transferrin can indicate poor protein status.
Low transferrin saturation is helpful to diagnose iron deficiency in individuals with inflammatory diseases, such as inflammatory bowel disease, chronic kidney disease, cancer, and heart failure, in whom serum ferritin levels may be elevated due to inflammation.
Transferrin levels are commonly measured alongside:
– Serum iron – Total iron-binding capacity (TIBC) – Ferritin – Complete blood count (CBC)