From the Guidelines
The TSAT formula is calculated as TSAT (%) = (Serum Iron ÷ TIBC) × 100, which is a crucial measure for assessing iron status in the body. This calculation is based on the serum iron concentration and total iron-binding capacity (TIBC), providing valuable information about the percentage of transferrin that is saturated with iron 1. The formula is essential for diagnosing and monitoring iron deficiency and iron overload conditions.
- The physiological basis for this measurement relates to transferrin's role as the primary iron transport protein in blood, carrying iron from absorption sites and storage locations to tissues that require iron for various metabolic processes, particularly red blood cell production.
- Normal TSAT values typically range from 20-50%, with values below 20% suggesting iron deficiency and values above 50% potentially indicating iron overload conditions like hemochromatosis 1.
- TSAT is particularly useful when interpreted alongside other iron markers such as ferritin, as it reflects the iron available for immediate use in the body.
- The calculation of TSAT is straightforward, involving the division of serum iron concentration by TIBC and multiplication by 100 to express the result as a percentage, as supported by recommendations to prevent and control iron deficiency in the United States 1.
From the Research
TSAT Formula
The TSAT (Transferrin Saturation) formula is calculated by dividing serum iron by Total Iron Binding Capacity (TIBC) and multiplying by 100.
- The formula is: TSAT = (Serum Iron / TIBC) * 100
- This calculation is used to determine the percentage of transferrin that is saturated with iron, which can help diagnose iron deficiency or iron overload 2, 3.
Reference Ranges
Reference ranges for serum iron and TSAT have been established in various studies:
- A study of over 55,000 Caucasians found that iron and TSAT levels rose slightly until the teen years, and then remained relatively constant in females, while increasing in males 2.
- Another study found that the mean serum iron concentration was 138.3 +/- 4.3 mug/100 ml, and the mean TIBC was 470.1 +/- 6.8 mug/100 ml, with a mean plasma siderophilin saturation of 30.0% 3.
Clinical Relevance
The TSAT formula has clinical relevance in diagnosing iron deficiency or iron overload:
- A study found that serum ferritin was the best predictor of body iron stores, but the correlation between serum ferritin and TSAT was not very strong 4.
- Another study found that serum iron and TIBC gave no additional information in the diagnosis of iron deficiency anemia, and these tests were redundant if serum ferritin was available 5.