Iron Panel Interpretation and Management
The interpretation of an iron panel requires evaluation of serum ferritin, transferrin saturation, and hemoglobin levels, with iron deficiency defined as ferritin <30 μg/L (or <45 ng/mL) and transferrin saturation <16%, while iron overload is characterized by elevated ferritin (>500 μg/L) and transferrin saturation (>45%).
Iron Panel Components and Normal Values
An iron panel typically includes:
- Serum ferritin: Measures iron stores
- Transferrin saturation (TSAT): Reflects iron available for erythropoiesis
- Serum iron: Direct measurement of circulating iron
- Total iron binding capacity (TIBC): Reflects transferrin's capacity to bind iron
- Hemoglobin: For assessment of anemia
| Parameter | Normal Value | Iron Deficiency | Iron Overload |
|---|---|---|---|
| Serum Ferritin | 30-300 μg/L | <30 μg/L | >500 μg/L |
| Transferrin Saturation | 16-45% | <16% | >45% |
| Hemoglobin | >12 g/dL (women), >13 g/dL (men) | <12 g/dL (women), <13 g/dL (men) | Normal or elevated |
Interpreting Iron Deficiency
Iron deficiency progresses through several stages:
- Iron depletion: Low ferritin with normal TSAT and hemoglobin
- Iron-deficient erythropoiesis: Low ferritin, low TSAT, normal hemoglobin
- Iron deficiency anemia: Low ferritin, low TSAT, low hemoglobin
Important considerations:
- Ferritin is an acute phase reactant and may be falsely elevated in inflammatory conditions 1
- Additional markers like mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), and red cell distribution width (RDW) can support diagnosis
- In chronic inflammation, functional iron deficiency may occur despite normal iron stores 1
Interpreting Iron Overload
Iron overload is characterized by:
- Elevated ferritin (>500 μg/L)
- Increased transferrin saturation (>45%)
- Potential organ damage (liver, heart, pancreas)
Causes include:
- Hereditary hemochromatosis (HFE gene mutations)
- Repeated blood transfusions
- Chronic liver disease
- Excessive iron supplementation
Management of Iron Deficiency
Oral Iron Therapy
- First-line treatment: Ferrous sulfate 200 mg three times daily (providing 65 mg elemental iron per tablet) 2
- Alternative formulations if not tolerated:
- Ferrous gluconate 300 mg (37 mg elemental iron)
- Ferrous fumarate 210 mg (69 mg elemental iron)
- Continue therapy for 3 months after hemoglobin normalization to replenish iron stores 2
- Expected response: Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks 2
Intravenous Iron Therapy
Indications:
- Intolerance to oral iron
- Poor response to oral iron
- Malabsorption conditions
- Ongoing blood loss
- Need for rapid repletion
Options:
- Ferric carboxymaltose: Can be administered as 750-1000 mg in a single dose 3
- Iron sucrose: Administered in divided doses (typically 200 mg per dose) 4
Management of Iron Overload
Phlebotomy
- Primary treatment for hereditary hemochromatosis and most cases of iron overload
- Initial regimen: Weekly removal of 500 mL blood until ferritin <50-100 μg/L 1
- Maintenance: Phlebotomy every 2-4 months to maintain ferritin <50-100 μg/L 1
Iron Chelation Therapy
- For transfusional iron overload or when phlebotomy is contraindicated
- Options include deferasirox, deferoxamine, and deferiprone
- Requires close monitoring for side effects
Special Considerations
Diagnostic Workup for Iron Deficiency
- For men and postmenopausal women with iron deficiency anemia: Bidirectional endoscopy (colonoscopy and upper endoscopy) is strongly recommended 1
- For premenopausal women: Consider initial empiric iron supplementation, but persistent or severe anemia may warrant endoscopic evaluation 1
Inflammatory Conditions
- In chronic inflammation, interpret ferritin with caution (may be falsely elevated)
- Consider using higher ferritin cutoff values (e.g., <100 μg/L) in inflammatory states 1
- Evaluate for functional iron deficiency (normal ferritin but low TSAT)
Athletes and Women of Reproductive Age
- Higher risk of iron deficiency due to increased losses and demands
- Consider regular screening and prophylactic supplementation 1
- Monitor for impact on performance and quality of life
Pitfalls to Avoid
- Relying solely on hemoglobin: Iron deficiency can exist without anemia 5
- Misinterpreting ferritin in inflammation: Use other markers and clinical context
- Inadequate duration of iron therapy: Continue treatment until stores are replenished
- Overlooking underlying causes: Always investigate the cause of iron deficiency or overload
- Excessive iron supplementation: Can lead to iron overload and toxicity 6
By systematically evaluating the iron panel components and understanding their interrelationships, clinicians can accurately diagnose iron disorders and implement appropriate treatment strategies to improve patient outcomes.