From the Guidelines
Transferrin and transferrin saturation are distinct measurements in iron metabolism, with transferrin saturation being a calculated percentage indicating how much of the available transferrin is carrying iron, and it is the most useful measurement for diagnosing iron-related disorders. Transferrin is a protein produced by the liver that transports iron in the bloodstream, binding to iron and delivering it to tissues that need it, serving as the primary carrier of iron in the blood 1. Transferrin saturation, on the other hand, is calculated by dividing serum iron by total iron-binding capacity (TIBC) and multiplying by 100, as described in the guidelines for preventing and controlling iron deficiency 1. This measurement helps assess iron status in the body, with normal transferrin saturation ranges from 20-50%, and values below 20% suggesting iron deficiency, while values above 50% potentially indicating iron overload conditions like hemochromatosis 1.
Key Differences
- Transferrin levels indicate the transport capacity for iron
- Transferrin saturation provides insight into the actual iron status and utilization of that capacity
- Transferrin saturation is a more useful measurement for diagnosing iron-related disorders, such as hemochromatosis, as it can indicate increased intestinal iron absorption and iron release from macrophages 1
- Transferrin saturation can also be increased in patients with advanced cirrhosis, low transferrin, acute liver failure, and acute liver injury, which can be confused with a predisposition to haemochromatosis 1
Clinical Implications
- Transferrin saturation should be used as a primary diagnostic tool for iron-related disorders, as it provides a more accurate assessment of iron status and utilization 1
- Normal transferrin saturation ranges should be used as a reference point for diagnosing iron deficiency and iron overload conditions 1
- Clinicians should be aware of the potential for increased transferrin saturation in patients with advanced cirrhosis, low transferrin, acute liver failure, and acute liver injury, and take this into consideration when diagnosing and treating iron-related disorders 1
From the Research
Definition of Transferrin and Transferrin Saturation
- Transferrin is a protein that binds free iron in the blood and bodily fluids, functioning to deliver iron to cells via a receptor-mediated endocytotic process, as well as to remove toxic free iron from the blood 2.
- Transferrin saturation, on the other hand, refers to the percentage of transferrin that is saturated with iron, and is widely considered the preferred screening test for hemochromatosis 3.
Difference between Transferrin and Transferrin Saturation
- Transferrin saturation is a measure of the amount of iron bound to transferrin, whereas transferrin itself is the protein that binds the iron 4.
- Total Iron-Binding Capacity (TIBC) is a measure of the total amount of iron that can be bound by transferrin, and is often used in conjunction with transferrin saturation to diagnose iron overload or deficiency 3.
Clinical Significance of Transferrin Saturation
- Transferrin saturation is an important indicator of iron status, and elevated levels can indicate iron overload, while low levels can indicate iron deficiency 5.
- The goal of treatment for patients with hereditary hemochromatosis is to keep transferrin saturation below 70% to prevent the formation of non-transferrin-bound iron and labile plasma iron 5.
Measurement of Transferrin Saturation
- Transferrin saturation can be measured using various methods, including quantitative electron spin resonance technique 4 and urea polyacrylamide gel electrophoresis (PAGE) 6.
- The measurement of transferrin saturation can be affected by various factors, including the type of iron preparation used 6 and the presence of other medical conditions 3.