Lab marker
Iron studies
Transferrin saturation (TSAT) · Serum iron · TIBC
The four-marker panel that resolves ferritin's ambiguity, distinguishing true iron status from inflammation-driven readings.
What it measures
Serum iron, total iron-binding capacity (TIBC, ~ transferrin), transferrin saturation (TSAT = serum iron / TIBC × 100), and ferritin together. Each tells a different part of the iron-status story; the combination resolves ambiguity that ferritin alone cannot.
Reference context
4 guideline sources
Single readings of serum iron and TSAT vary diurnally (peak morning, trough evening) and after meals. For trending, sample at the same time of day under similar conditions. TSAT is the most clinically useful single iron-study output when ferritin is ambiguous.
Population context: consult guideline targets below
Mechanism
Why moving this marker matters
Ferritin reflects stored iron but is also an acute-phase reactant: it rises in inflammation, infection, liver disease, malignancy, and recent exercise. When ferritin is elevated, TSAT distinguishes true overload (high TSAT) from inflammation-confounded reading (low/normal TSAT). When ferritin is low-normal, TSAT < 20% suggests functional iron deficiency.
Guideline targets
What major guidelines recommend
Common reference (TSAT, normal)
20–50%
BSH 2021 (TSAT, functional iron deficiency)
<20%
EHRS / haemochromatosis (TSAT, suggestive of overload)
>45% in women / >50% in men
Serum iron (typical reference)
10–30 µmol/L (assay-dependent)
How to measure
The test, where to get it, when to repeat
Method
Standard panel: single blood draw for ferritin, serum iron, TIBC, and TSAT (computed). Pair with CRP to flag inflammation.
Where
GP request or comprehensive private panel.
Typical cost
€20–50 for full panel.
Fasting
Not required
When to test
BSH 2021
Order alongside ferritin when symptoms suggest iron deficiency despite normal ferritin, or when ferritin is elevated and overload is being considered.
Where to test
Independent labs offering this test
Healicus refers you to independent laboratories. You order from the lab; they take the sample, run it, and return your result on their own platform. Healicus never sees your value.
Randox Health
UK · EU · INTLClinic-based premium panels — wider biomarker breadth than home-test brands.
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Synlab
DE · EU · INTLEurope-wide medical lab network — referrals via partner GPs and direct-to-consumer programmes where offered.
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Medichecks
UKUKAS-accredited home blood-test panels with GP-equivalent biomarker coverage.
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Thriva
UKApp-first subscription home testing, capillary draw, clinician-reviewed reports.
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Context
Reading the numbers
Single readings of serum iron and TSAT vary diurnally (peak morning, trough evening) and after meals. For trending, sample at the same time of day under similar conditions. TSAT is the most clinically useful single iron-study output when ferritin is ambiguous.
Caveats
Acute iron supplementation in the prior 24 hours falsely elevates serum iron and TSAT. Chronic inflammation lowers TSAT (anaemia of inflammation pattern: low TSAT + high or normal ferritin).
Practices
What's been shown to influence this marker
Mediterranean pattern provides both heme iron (fish, modest meat) and non-heme iron (legumes, leafy greens), with ascorbate-rich foods enhancing non-heme absorption. Adequate iron status in most adherent adults.
Heavy alcohol intake is a recognised driver of iron overload (alcoholic siderosis) and confounds ferritin interpretation. Reduction is first-line management in suspected alcohol-related iron elevation.
HabitMediterranean dietary pattern
Olive oil, fish, nuts, legumes, plants. The most-studied diet for cardiovascular and cognitive longevity.
Why
The Mediterranean pattern, heavy on plants, olive oil, fish, nuts, legumes; moderate fish and dairy; light on red meat, has the strongest evidence base of any specific diet for long-term cardiovascular and cognitive outcomes. PREDIMED, the largest trial, showed ~30% reduction in major cardiovascular events vs. low-fat control.
Slot in your day
How to do it
How
Olive oil as the primary fat. Plants at every meal. Fish 2–3× per week. Nuts daily (small handful). Red meat once a week or less. Wine optional, with food.
Sticking with it
Stock the kitchen for one week's pattern. Decisions live in the shopping list, not at mealtime.
Markers this may influence
Evidence
PREDIMED (Estruch 2018 NEJM, n=7,447, 4.8-y follow-up): a Mediterranean diet plus extra-virgin olive oil or mixed nuts vs. a low-fat control diet, ~30% reduction in major cardiovascular events (MI, stroke, CVD death). Sofi 2014 updated meta-analysis (n>4M) confirms a dose-response association with all-cause and cardiovascular mortality.
CautionHabitLimit alcohol intake
Lancet pooled analysis (n=599,912): lowest mortality risk threshold is ~100 g/week, about 5-6 standard drinks total.
Why
Wood et al. 2018 Lancet combined individual-participant data from 83 prospective studies (n=599,912 current drinkers in 19 high-income countries). Above ~100 g/week (about 5-6 UK standard units), all-cause mortality climbs in a dose-response manner. Below that threshold the curve is roughly flat, there is no protective effect. Reductions from heavier intake to ≤100 g/week could add up to 2 years of life expectancy at age 40.
How to do it
How
Track intake honestly for one week. If above threshold, set a weekly cap rather than a daily one (avoids the 'I'll catch up' trap). Several alcohol-free days per week is the simplest pattern. Sleep quality typically improves within 1-2 weeks of reduced intake.
Ideal for
Anyone currently drinking above ~100 g/week (≈one bottle of wine, six pints of beer, or a half-bottle of spirits).
Markers this may influence
Evidence
Wood 2018 Lancet pooled analysis (83 prospective studies, n=599,912 current drinkers across 19 high-income countries): the threshold for lowest all-cause mortality was ~100 g alcohol/week (≈5–6 UK units). Above that, intake is linearly associated with mortality and reduces life expectancy by 1–2 years at age 40 for 200–350 g/week drinkers.
See also
Related markers
Take to your physician
Worth discussing
- Whether TSAT clarifies a borderline ferritin reading in your case.
- If TSAT is persistently elevated (>45–50%), whether haemochromatosis screening (HFE genotype) is warranted.
- If TSAT is low with normal Hb, whether functional iron deficiency warrants intervention.
Sources
Cited literature
- [1]British Society for Haematology, UK guidelines on the management of iron deficiency(2021)
- [2]European Haemochromatosis Reference Standard, diagnosis and management thresholds(2018)
- [3]Ioannou et al., The effect of alcohol consumption on the prevalence of iron overload, iron deficiency, and iron deficiency anemia (Gastroenterology)(2004)
Last reviewed May 2026
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