Transferrin transports circulating Fe3+ molecules. Normally only about one third of iron-binding sites are occupied (the remainder is called unsaturated iron-binding capacity). The half-life of transferrin is approximately 8 " “10 days. Plasma levels are regulated primarily by availability of iron, iron deficiency anemia. Plasma levels rise on successful treatment with iron and return to normal.
Normal range: 202 " “336 mg/dL.
Use
Differential diagnosis of anemias
Interpretation
Increased In
Iron deficiency anemia; inversely proportional to iron stores
Pregnancy, estrogen therapy, hyperestrogenism
Decreased In
Hypochromic microcytic anemia of chronic disease
Acute inflammation
Protein deficiency or loss (e.g., burns, chronic infections, chronic diseases [e.g., various liver and kidney diseases, neoplasms], nephrosis, malnutrition)
Limitations
Transferrin in CSF appears in its desialated form, the Tau protein (beta-2-transferin). This form can be identified electrophoretically. The clinical application for identification of Tau protein is in the investigation of rhinorrhea or otorrhea, where its presence confirms the source of CSF leakage through a fracture or operative or traumatic site.
Partly desialated transferrin is a marker for heavy alcohol ingestion.