Iron Studies Interpretation in an 86-Year-Old Patient
These lab values indicate adequate iron stores with a low-normal TIBC, which most likely reflects either chronic inflammation, adequate iron status, or chronic disease rather than iron deficiency—no iron supplementation is indicated. 1
Understanding the Lab Pattern
Your patient's iron panel shows:
- Serum iron: 74 µg/dL (normal) - adequate circulating iron 1
- TIBC: 234 µg/dL (low) - below the typical reference range of 250-370 µg/dL 1
- Transferrin saturation: 32% (normal) - well above the 20% threshold for adequacy 1
- Ferritin: 174 ng/mL (normal) - adequate iron stores 1
Clinical Significance
The combination of normal iron, normal ferritin, normal transferrin saturation, but LOW TIBC is NOT consistent with iron deficiency. 1 This pattern typically indicates:
- Inflammation or chronic disease: TIBC decreases in inflammatory states because it reflects transferrin levels, which behave as a negative acute phase reactant 1
- Adequate iron stores: The ferritin of 174 ng/mL is well above deficiency thresholds (>100 ng/mL for most populations, >30 ng/mL for healthy adults) 1, 2
- Sufficient functional iron: The transferrin saturation of 32% exceeds the 20% minimum threshold needed for adequate erythropoiesis 1
Key Diagnostic Considerations
In iron deficiency, you would expect:
- Low serum iron 1
- HIGH TIBC (>370 µg/dL) as the body attempts to capture more iron 1, 3
- Low transferrin saturation (<20%) 1
- Low ferritin (<30-100 ng/mL depending on population) 1, 2
Your patient has the opposite pattern for TIBC, which rules out iron deficiency. 3
Management Recommendations
No iron supplementation should be given. 1, 2 Iron supplementation in the presence of normal or elevated ferritin values is not recommended and is potentially harmful. 1, 2
Next Steps:
- Check for inflammation: Measure C-reactive protein (CRP) to assess for acute or chronic inflammatory conditions that could explain the low TIBC 1, 2
- Evaluate for chronic disease: Consider underlying conditions common in elderly patients (chronic kidney disease, heart failure, malignancy, chronic infections) that can cause anemia of chronic disease with this iron pattern 1
- Check hemoglobin: If not already done, assess whether anemia is present—this pattern can occur with anemia of chronic disease where iron is sequestered but stores are adequate 1
Important Caveats
TIBC alone is less diagnostically useful than transferrin saturation and ferritin combined. 3 Studies show that transferrin or TIBC measurement outperforms iron measurement alone (ROC AUC 0.94 vs 0.77), but the combination of markers provides the most complete picture. 3
In elderly patients, ferritin can be falsely elevated by inflammation, making it less reliable as a sole marker. 1 However, with a normal transferrin saturation of 32%, functional iron availability is clearly adequate regardless of the ferritin interpretation. 1
The low TIBC in this context suggests looking beyond simple iron deficiency and considering systemic processes affecting iron metabolism, particularly given the patient's age. 1, 4