Transferrin (siderophilin)
Martial balance parameters and their relations
- Serum iron (sideremia): transferrin-bound circulating iron concentration + normal: 10–30 µmol/L + highly variable depending on meals + stress + time of collection (significant circadian variations — maximum in the morning) → collect in the morning after fasting + unreliable marker on its own
- Serum transferrin Transferrin concentration + normal: 2.0–3.5 g/L + increased in iron deficiency + decreased in inflammation + liver disease + malnutrition + iron overload
- TIBC (Total Iron-Binding Capacity): CTF = maximum iron binding capacity + calculated or measured + CTF = transferrin (g/L) x 25 (approximately) + normal: 45-70 µmol/L + increased if transferrin is high (iron deficiency) + decreased if transferrin is low (inflammation + liver disease)
- Transferrin saturation (Tsat): Tsat = (serum iron / TI) × 100 + normal range: 20–45 % + low (<20 %) = "carence" en fer ou anémie des maladies chroniques + élevée (>45–50 (%) = iron overload (hemochromatosis) + the most informative parameter in the iron panel
- Serum ferritin reflects iron reserves in the reticuloendothelial system + normal: 15–300 µg/L + low (<15 µgl) = "carence" en fer certaine + élevée (>300–400 µg/L) = surcharge + or inflammation + or hepatopathy + or metabolic syndrome + ferritin is a positive acute phase reactant → can be falsely normal or elevated despite deficiency if inflammation is concomitant
Combined Interpretation — Common Diagnostics
| Diagnosis | Ferritin | Serum iron | Transferrin / CTF | Saturation Temperature |
|---|---|---|---|---|
| Iron deficiency (iron-deficiency anemia) | Low (<15 µg/L) | Low | Elevated (hepatic compensation) | Low (<20 %) |
| Anemia of chronic disease (ACD) | Normal or high (acute phase reactant) | Low | Low or normal (negative reactant) | Low or normal low |
| Deficiency + concomitant inflammation | Variable (can be normal despite deficiency) | Low | Variable | Low (<20 %) |
| Hereditary Hemochromatosis (HFE) | Very high (>300–1000 µg/L) | High | Low or normal | Very high (>45–60 %) |
| Iron overload | Very high | High | Low | Very high |
| Liver disease (cirrhosis) | Variable (elevated by cytolysis) | Variable | Low (reduced hepatic synthesis) | Elevated (low transferrin → falsely high saturation) |
| Pregnancy (2nd–3rd trimester) | Bass (increased needs) | Low | Raised (increased needs) | Low |
| Normal | 15–300 µg/L | 10–30 micromoles per liter | 0.2–0.35% (CTF 45–70 µmol/L) | 20–45 % |
Transferrin and hereditary hemochromatosis
- Hemochromatosis Screening: Fasting transferrin saturation > 45 % (women) or > 50 % (men) = warning threshold → indication for HFE genetic testing (C282Y + H63D mutations) → if C282Y homozygosity confirmed → ferritin to assess the degree of overload → liver biopsy if ferritin > 1,000 µg/L or elevated transaminases (assessment of fibrosis)
- Meaning of high TSH: Transferrin saturation is the most sensitive screening test for hemochromatosis (sensitivity 90–95% if Tsat > 45%) but false positives are possible (alcoholic liver disease, MASLD, hemolytic anemia, postprandial sampling)
- Hemochromatosis Treatment: Therapeutic phlebotomies (bloodlettings) → ferritin target < 50 µg/L + transferrin saturation < 50 % → followed by ferritin + CBC + HbA1c every 2–4 months
Transferrin and Anemia of Chronic Disease (ACD) vs. Iron Deficiency
- Common clinical problem: Distinguishing true iron deficiency from anemia of chronic disease (in the context of chronic inflammation - CKD + cancer + inflammatory bowel disease) because the treatment differs (iron supplementation vs. treating the cause + erythropoietin).
- AMC pure Normal or elevated ferritin (positive acute phase reactant) + low transferrin (negative reactant) + normal-low Tsat + normal soluble transferrin receptor (sTfR)
- Pure iron deficiency: Low ferritin + high transferrin + low Tsat + high sTfR
- Deficiency + inflammation ferritin can be falsely normal (between 15 and 100 µg/L) + low Tsat + high sTfR → the sTfR/log(ferritin) index (Thomas index) can help distinguish: > 2 = iron deficiency + 1 = AMC Pure
Consult a doctor if a blood test shows an abnormally high transferrin saturation (>45–50% %) or very high ferritin (>500–1,000 µg/L) with no obvious explanation—these values warrant an HFE genetic test to rule out hereditary hemochromatosis. Low saturation (< 20% %) with low ferritin confirms iron deficiency requiring replacement therapy and investigation of the cause. For a comprehensive iron panel (iron + transferrin + CTF + saturation + ferritin) and interpretation within the clinical context, Clinique Omicron offers consultations at its service locations in Quebec and via telemedicine. To schedule an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's physician associates and nurse practitioners (IPs) prescribe and interpret a complete iron panel (ferritin + iron + transferrin + TIBC + transferrin saturation) within its clinical context, differentiate iron deficiency anemia from anemia of chronic disease, screen for hereditary hemochromatosis using transferrin saturation, and refer for HFE genetic testing if indicated. They initiate iron deficiency treatment (oral ferrous sulfate + IV iron based on tolerance) and coordinate with gastroenterology and hematology for complex investigations. Consultations are available at multiple locations in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is provided for informational purposes only and does not replace the advice of a doctor or hematologist. Ferritin is an acute phase reactant that can be falsely normal or elevated in chronic inflammation despite iron deficiency — always interpret ferritin in its clinical context and in combination with transferrin saturation. Transferrin saturation should be measured on an empty stomach in the morning to avoid postprandial variations.
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