From the Guidelines
To calculate transferrin saturation, divide your serum iron level by your total iron binding capacity (TIBC) and multiply by 100 to get a percentage, as indicated by the formula: Transferrin Saturation (%) = (Serum Iron ÷ TIBC) × 100 1.
Understanding Transferrin Saturation
Transferrin saturation is a crucial marker for assessing iron status, reflecting the proportion of iron-binding sites on transferrin proteins that are occupied by iron molecules. This measurement provides insight into both iron deficiency and overload conditions.
- The formula for calculating transferrin saturation is straightforward and relies on the serum iron level and the total iron binding capacity (TIBC).
- For instance, if your serum iron is 80 μg/dL and your TIBC is 300 μg/dL, your transferrin saturation would be (80 ÷ 300) × 100 = 26.7% 1.
Interpreting Results
Normal transferrin saturation typically ranges from 20% to 50% in healthy adults.
- Values below 20% may indicate iron deficiency, a condition where the body lacks sufficient iron for optimal erythropoiesis.
- Values above 50% could suggest iron overload conditions like hemochromatosis, where excessive iron accumulation can lead to tissue damage.
Clinical Considerations
In clinical practice, distinguishing between absolute and functional iron deficiency is crucial, especially in patients with chronic kidney disease (CKD) or those undergoing erythropoiesis-stimulating therapy 1.
- Absolute iron deficiency is characterized by depleted iron stores, whereas functional iron deficiency occurs when there is a need for more iron to support erythropoiesis than can be released from stores.
- The distinction between these conditions can significantly impact treatment decisions, including the use of intravenous iron and erythropoietin-stimulating agents.
From the Research
Transferrin Saturation Calculator
- Transferrin saturation (TSAT) is a measure of the amount of iron-bound transferrin in the blood, and it is an important indicator of iron overload or deficiency 2, 3.
- TSAT is calculated by dividing the serum iron level by the total iron-binding capacity (TIBC) and multiplying by 100 2.
- A high TSAT level (> 70%) indicates iron overload, while a low TSAT level (< 25%) indicates iron deficiency 2, 4.
- Several studies have investigated the use of TSAT as a predictor of response to iron chelation therapy or phlebotomy in patients with iron overload disorders, such as thalassemia and hemochromatosis 2, 5, 3.
- For example, a study published in the American Journal of Hematology found that early start of iron chelation therapy with deferiprone in young children with transfusion-dependent thalassemia delayed the time to reach a serum ferritin level > 1000 μg/L and reduced the risk of iron accumulation 2.
- Another study published in the Journal of Trace Elements in Medicine and Biology found that phlebotomy and chelation are effective treatments for iron overload, and that combined subcutaneous and oral treatment with deferoxamine and deferiprone may be particularly effective 5.
Calculation of Transferrin Saturation
- The calculation of TSAT involves measuring the serum iron level and TIBC, and then using the following formula: TSAT = (serum iron / TIBC) x 100 2.
- The normal range for TSAT is typically considered to be between 25% and 50% 4.
- TSAT levels above 70% may indicate iron overload, while levels below 25% may indicate iron deficiency 2, 4.
Clinical Significance of Transferrin Saturation
- TSAT is an important indicator of iron status and can be used to monitor the effectiveness of iron chelation therapy or phlebotomy in patients with iron overload disorders 2, 5, 3.
- Elevated TSAT levels have been associated with an increased risk of cardiovascular disease, liver disease, and other complications in patients with iron overload disorders 5, 3.
- Regular monitoring of TSAT levels can help healthcare providers adjust treatment plans and prevent complications in patients with iron overload disorders 2, 5, 3.