Transferrin (siderophilin)
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Martial Balance Settings and Their Relationships
- 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 / TIBC) × 100 + normal: 20–45 %+ low (45–50 % ) = iron overload (hemochromatosis) + the most informative parameter of the iron panel
- Serum ferritin: reflects the iron reserves of the reticuloendothelial system + normal: 15–300 µg/L + low (300–400 µg/L) = overload + or inflammation + or liver disease + or metabolic syndrome + ferritin is a positive acute phase reactant → can be falsely normal or elevated despite deficiency if there is concomitant inflammation
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) | Raised | Low or normal | Very high (>45–60 %) |
| Iron overload | Very high | Raised | Low | Very high |
| Liver disease (cirrhosis) | Variable (elevated by cytolysis) | Variable | Basse (reduced hepatic synthesis) | Elevated (low transferrin → falsely high saturation) |
| Pregnancy (2nd–3rd trimester) | Bass (increased needs) | Low | Elevated (increased needs) | Low |
| Normal | 15–300 µg/L | 10–30 micromoles per liter | 2.0–3.5 g/L (CTF 45–70 µmol/L) | 20–45 % |
Transferrin and hereditary hemochromatosis
- Hemochromatosis screening: saturation de la transferrine à jeun > 45 % (femme) ou > 50 % (homme) = seuil d'alerte → indication de test génétique HFE (mutations C282Y + H63D) → si C282Y homozygote confirmé → ferritine pour évaluer le degré de surcharge → biopsie hépatique si ferritine > 1 000 µg/L ou transaminases élevées (évaluation de la fibrose)
- Meaning of a high Tsat: 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 sample)
- Treatment of hemochromatosis: therapeutic phlebotomy (bloodletting) → target ferritin < 50 µg/L + transferrin saturation < 50% % → follow-up with ferritin + CBC + Tsat 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 = pure ACD
Consult a doctor if a iron panel shows an abnormally high transferrin saturation (> 45–50 %) or very high ferritin (> 500–1,000 µg/L) without an 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 into the cause. For a complete iron panel (iron + transferrin + TIBC + saturation + ferritin) and interpretation in a clinical context, Clinique Omicron offers consultations at its service points in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's nurse practitioners (NPs) prescribe and interpret complete iron studies within their clinical context (ferritin + iron + transferrin + TIBC + transferrin saturation), 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 as tolerated) and coordinate with gastroenterology and hematology for complex investigations. Consultations are available at multiple service points across Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not substitute for advice from a physician or hematologist. Ferritin is an acute phase reactant that can be falsely normal or elevated in chronic inflammation despite iron deficiency—always interpret ferritin within its clinical context and in combination with transferrin saturation. Transferrin saturation should be measured in the morning on an empty stomach to avoid postprandial variations.
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