Related Subjects:
|Ferritin
|CEA
|ESR
|CRP
|ALP
|LDH
|HbA1c
|Alpha Fetoprotein
|Anti-Hu ab
|Anti-Yo ab
|Biochemical Lab values
๐ฉธ Iron studies help differentiate iron deficiency anaemia (IDA) from anaemia of chronic disease (AOCD), acute phase reactions, and iron overload.
๐ IDA = ferritin low, TIBC/transferrin high.
๐ AOCD = ferritin normal/high (APR), iron low, TIBC low.
| Iron Deficiency Anaemia | Anaemia of Chronic Disease | Acute Phase Reaction | Iron Overload |
| Serum Iron | โฌ Low | โฌ Low | โฌ Low | โฌ High |
| Transferrin / TIBC | โฌ High | โฌ Low | โฌ Low | โฌ/โ Low/Normal |
| Transferrin Saturation | โฌ Low | โฌ Low | โฌ Low | โฌ High |
| Ferritin | โฌ Low | โ Normal (โ if APR) | โฌ High | โฌ High |
| Soluble Transferrin Receptor | โฌ High | โ Normal | โ Normal | โฌ Low |
๐น Ferritin
- Main intracellular storage form of iron โ each molecule can hold ~4500 Fe atoms.
- Acute phase reactant: can be elevated in infection/inflammation even if iron deficient.
- Diagnostic cut-offs: Ferritin <15 ฮผg/L is very specific for IDA; <30 ฮผg/L often used in practice (higher cut-offs in chronic inflammation/CKD).
- >1000 ฮผg/L โ consider haemochromatosis or chronic liver disease.
๐น Serum Iron
- Reflects ferric (Feยณโบ) ions bound to transferrin.
- Highly variable - affected by meals, diurnal rhythm, and illness โ not reliable in isolation.
- <10 ฮผmol/L = likely deficiency; >30 ฮผmol/L = overload.
๐น Transferrin
- Iron-transport protein (apotransferrin) carrying 1โ2 Fe atoms.
- โฌ Rises in IDA to maximise uptake.
- โฌ Falls in liver disease, inflammation, nephrotic syndrome.
๐น Transferrin Saturation
- Calculated:
(Serum iron รท TIBC) ร 100.
- Normal โ 30% saturated.
- <16% = iron deficiency.
>45% = possible overload.
>55% in men / >50% in women = screen for haemochromatosis.
๐น Total Iron Binding Capacity (TIBC)
- Reflects binding site availability on transferrin.
- โฌ High in IDA (>70 ฮผmol/L).
โฌ Low in overload (<45 ฮผmol/L).
๐ Diagnostic Criteria for Iron Deficiency Anaemia
- Ferritin <15 ฮผg/L (or <30 ฮผg/L depending on guidelines).
- Transferrin saturation <16%.
- Hb below reference (WHO cut-offs: <120 g/L women, <130 g/L men โฅ15 yrs).
- Therapeutic trial: Hb rise โฅ1 g/dL after ~8 weeks of iron therapy supports diagnosis.
๐ก Teaching pearl:
Ferritin is the most reliable single marker of iron stores. Always interpret in context:
- Low ferritin = IDA.
- Normal ferritin does not exclude IDA if inflammation, CKD, or malignancy present โ check transferrin saturation and CRP.
