Transferrin saturation (TSAT) is calculated using different formulas, each requiring different lab values. Here are the two common methods used in clinical practice:
TSAT Calculation Formulas
According to references [1,2], TSAT can be calculated using two different formulas, depending on the available laboratory values:
| Formula | Calculation | Required Lab Values |
|---|---|---|
| 1 | TSAT = (Fe/TIBC) × 100 | Serum Iron (Fe) and Total Iron-Binding Capacity (TIBC) |
| 2 | TSAT = (Fe/TF) × 70.9 | Serum Iron (Fe) and Transferrin (TF) Concentration |
Understanding the Formulas
- Formula 1: Using Serum Iron and TIBC:
- This method calculates TSAT by dividing the serum iron (Fe) concentration by the total iron-binding capacity (TIBC) and then multiplying the result by 100 to express the value as a percentage [1,2].
- Example: If Serum Iron (Fe) is 80 mcg/dL and TIBC is 300 mcg/dL, the TSAT would be (80/300) x 100 = 26.7%.
- Formula 2: Using Serum Iron and Transferrin:
- In this method, TSAT is determined by dividing the serum iron concentration (Fe) by the transferrin (TF) concentration and then multiplying the result by 70.9 [1,2].
- Example: If Serum Iron (Fe) is 80 mcg/dL and Transferrin (TF) is 250 mg/dL, the TSAT would be (80/250) x 70.9 = 22.7%.
Practical Insights
- The choice of formula depends on the laboratory tests available.
- Both formulas are designed to estimate the percentage of transferrin that is bound to iron.
- TSAT is an important marker for evaluating iron status in the body.
Conclusion
TSAT calculations utilize either serum iron and total iron-binding capacity (TIBC) or serum iron and transferrin (TF), each with their unique formula. The selection of the appropriate method depends on the lab data available, both providing an estimate for the amount of iron that is bound to transferrin.
