Hematology, quick reference 3 of 10
03 / 10 · Hematology
Iron study patterns
Deficiency, inflammation, mixed findings, and overload
Interpret the iron panel results together. Serum iron reflects circulating iron, and ferritin helps assess storage iron. Inflammation can sequester iron in storage and raise ferritin, so little iron is available for red cell production.1
Total iron-binding capacity (TIBC) reflects transferrin, the main iron transport protein. Transferrin saturation (TSAT) is the percentage of that capacity occupied by iron.1
Use the same concentration units for iron and TIBC.
Iron 30 µg/dL ÷ TIBC 300 µg/dL × 100 = 10% TSAT. µg/dL = micrograms per deciliter. A low TSAT occurs in both iron deficiency and inflammation.
Typical adult patterns1,2
↓ decreased; ↑ increased; N within the applicable reference interval.
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| Pattern | Serum iron | TIBC / transferrin | TSAT | Ferritin |
|---|---|---|---|---|
| Iron deficiency | decreased | increased | decreased | decreased |
| Anemia of inflammation | decreased | decreased or normal | decreased or normal | normal or increased |
| Mixed deficiency + inflammation | decreased | Variable, often normal or decreased | decreased | decreased, normal, or increased |
| Iron overload | Often increased | normal or decreased | Usually increased | Usually increased |
Why inflammation changes the panel
A low ferritin supports depleted stores. During inflammation, a normal or high ferritin cannot exclude deficiency, and liver injury can also raise ferritin. Hepcidin, an iron-regulating hormone, reduces iron release from stores and absorption from the gut. Inflammation can also lower transferrin. Mixed deficiency may then lack the high TIBC and low ferritin expected in iron deficiency.1,3
High ferritin alone does not establish overload. A persistently high TSAT makes overload more likely. Some overload disorders have a normal TSAT, so a normal value does not exclude overload.2
When results do not agree
Compare with hemoglobin, red cell indices, C-reactive protein or another inflammation marker, and collection and iron-treatment history.
Soluble transferrin receptor may help when inflammation obscures ferritin. Increased red cell production also raises it, and cutoffs vary by method. Reticulocyte hemoglobin reflects the iron available to recently produced red cells. It can be low in either deficiency or inflammation.1,3