What is the appropriate management for a 55-year-old female with low iron saturation, low iron, and high TIBC, despite a normal CBC?

Iron Deficiency Diagnosis and Management

The laboratory values indicate iron deficiency requiring oral iron supplementation despite the normal CBC. 1, 2

Interpretation of Laboratory Values

The patient's laboratory results show:

• Iron: 34 (low)
• TIBC: 0.85 (high)
• Iron saturation index: 0.85 (very low)
• Normal CBC

These findings are consistent with iron deficiency without anemia, which represents an early stage of iron depletion. The normal CBC indicates that the iron stores have been depleted, but the deficiency has not yet affected hemoglobin production enough to cause anemia 2, 3.

Key Diagnostic Considerations:

• Low transferrin saturation (<20%) is one of the most reliable indicators of iron deficiency 2
• Elevated TIBC is characteristic of iron deficiency as the body increases transferrin production to maximize iron transport 1, 4
• Normal CBC does not exclude iron deficiency, as hemoglobin and hematocrit decrease only when severe iron depletion is present 3

Management Recommendations

1. Oral Iron Supplementation:

   • Start ferrous sulfate 324 mg (65 mg elemental iron) once daily 2, 5
   • Once-daily dosing may be as effective as multiple daily doses with fewer side effects 2
   • Take on an empty stomach with vitamin C to enhance absorption 2

2. Monitoring:

   • Check hemoglobin, iron studies, and ferritin after 4-8 weeks of therapy 2
   • Target ferritin level >100 ng/mL and transferrin saturation >20% 2

3. Duration of Treatment:

   • Continue treatment for 3-6 months after normalization of iron indices to replenish iron stores 2

Evaluation for Underlying Causes

For a 55-year-old female with iron deficiency, investigate:

• Gastrointestinal blood loss (most common cause in postmenopausal women)
• Malabsorption disorders (celiac disease, H. pylori infection)
• Dietary insufficiency
• Potential malignancy

Potential Pitfalls

1. Diagnostic Pitfalls:

   • Relying solely on CBC without iron studies can miss iron deficiency before anemia develops 3
   • Ferritin levels may be falsely normal or elevated in inflammatory conditions 2

2. Treatment Pitfalls:

   • Inadequate duration of therapy leading to recurrence
   • Poor adherence due to gastrointestinal side effects
   • Failure to investigate underlying cause

Special Considerations

If oral iron is not tolerated or ineffective:

• Consider alternate-day dosing to improve tolerance
• Switch to a different iron formulation
• Consider IV iron if oral therapy fails or if rapid repletion is needed 2

Iron deficiency without anemia should be treated as aggressively as iron deficiency anemia to prevent progression to anemia and associated complications 2, 6.