From the Guidelines
Transferrin saturation is a key laboratory measurement that reflects the percentage of iron-binding sites on transferrin proteins that are occupied by iron, calculated by dividing serum iron by total iron binding capacity and multiplying by 100, with values below 20% suggesting iron deficiency and above 50% suggesting iron overload, as indicated by the most recent study 1.
Interpretation of Transferrin Saturation (TSAT)
The interpretation of TSAT is crucial in assessing iron deficiency or overload.
- A TSAT of less than 20% is often used to confirm iron deficiency, as seen in studies 1.
- Conversely, elevated TSAT above 50% suggests iron overload, which may be seen in conditions like hereditary hemochromatosis, multiple blood transfusions, or certain liver diseases, as indicated by 1.
- Particularly concerning are values above 75%, which strongly indicate hemochromatosis and warrant further investigation, as suggested by 1.
Factors Affecting TSAT Interpretation
When interpreting TSAT, it is essential to consider other iron parameters, including serum ferritin, complete blood count, and clinical symptoms.
- Inflammation can affect results by decreasing serum iron levels, potentially masking iron overload or falsely suggesting iron deficiency, so inflammatory markers should be considered when interpreting borderline results, as noted in 1.
- Fasting samples provide the most accurate results since recent iron intake can temporarily increase levels, as seen in 1.
Clinical Application
In clinical practice, TSAT is used to diagnose and manage iron deficiency and overload.
- A combination of TSAT, serum ferritin, and inflammatory markers can help differentiate between iron deficiency and anemia of chronic disease, as suggested by 1.
- MRI can be used to non-invasively quantify tissue iron concentrations and guide diagnosis and management, as indicated by 1. In summary, TSAT is a critical laboratory measurement that requires careful interpretation in the context of other iron parameters and clinical symptoms, with values below 20% suggesting iron deficiency and above 50% suggesting iron overload, as supported by the most recent study 1.
From the Research
Interpretation of Transferrin Saturation (TSAT)
- TSAT is a marker of iron deficiency, reflecting both serum concentrations of iron and transferrin 2
- It is susceptible to changes in serum iron and transferrin concentrations 2
- TSAT is used to evaluate iron status, with low TSAT levels indicating iron deficiency 3, 4
- A TSAT level <20% is often used as a cutoff for iron deficiency 3, 4
Clinical Significance of TSAT
- Low TSAT levels have been associated with increased mortality in patients with chronic heart failure 2, 4 and those on maintenance hemodialysis 3
- TSAT levels <20% have been shown to be a significant independent risk factor for all-cause mortality in patients on maintenance hemodialysis 3
- Elevated TSAT levels (≥45% for women and ≥50% for men) have been associated with worse general health status, mental health status, and shorter telomere length 5