Serum iron normal levels
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Here is a complete overview of normal serum iron levels and the full iron panel, drawn from authoritative medical textbooks.
Serum Iron - Normal Reference Ranges
| Parameter | Normal Range | SI Units |
|---|---|---|
| Serum Iron (Men) | 75-150 mcg/dL | 13-27 µmol/L |
| Serum Iron (Women) | 60-140 mcg/dL | 11-25 µmol/L |
| Serum Iron (General) | 50-170 mcg/dL | 9-27 µmol/L |
| TIBC (Total Iron-Binding Capacity) | 250-450 mcg/dL | 45-81 µmol/L |
| Transferrin Saturation | 25-50% | - |
| Serum Ferritin (Men) | ~100 ng/mL (avg) | - |
| Serum Ferritin (Women, premenopausal) | ~30 ng/mL (avg) | - |
| Serum Ferritin (General range) | 30-400 ng/mL | - |
Sources: Harrison's Principles of Internal Medicine 22E; Merck Manual; Biochemistry, Lippincott 8th ed.
Key Clinical Points
Why serum iron alone is unreliable:
- It fluctuates 20-30% diurnally - highest before 10 AM, lowest in the evening
- Rises transiently after meals or iron supplements
- Falls acutely with infection/inflammation (hepcidin-mediated sequestration)
- Always interpret alongside TIBC and transferrin saturation - "Obtaining a serum iron level without determining the level of transferrin (TIBC) is of limited value." (Textbook of Family Medicine 9e)
Interpreting the iron panel:
| Pattern | Serum Iron | TIBC | Ferritin | Transferrin Sat. | Diagnosis |
|---|---|---|---|---|---|
| Low | Low | High | Low | Low | Iron deficiency anemia |
| Low | Low | Normal/Low | Normal/High | Low | Anemia of chronic disease |
| Normal/High | Normal | Normal/Low | Normal/High | Normal/High | Thalassemia |
| High | High | Low/Normal | High | High | Hemochromatosis / iron overload |
Ferritin thresholds:
- < 10 ng/mL in women or < 20 ng/mL in men = almost always reflects low iron stores
- < 30 µg/L = depletion of body iron stores (Harrison's 22E)
-
200 µg/L = at least some iron in tissue stores
Note: Reference ranges vary slightly between laboratories. Morning fasting specimens are preferred for serum iron testing to align with the established reference intervals.
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