What is the appropriate management for an adult patient with iron deficiency anemia, as indicated by low iron levels, elevated Total Iron-Binding Capacity (TIBC), and low iron saturation, in the context of recent leukocytosis and normal red blood cell (RBC) and platelet counts?

Management of Iron Deficiency Based on Laboratory Values

Your laboratory results confirm iron deficiency (low iron 72, elevated TIBC 475, low transferrin saturation 15%), and you should initiate oral iron supplementation immediately while pursuing investigation for the underlying cause, particularly gastrointestinal evaluation given the recent leukocytosis. 1

Interpretation of Your Iron Studies

Your iron panel definitively demonstrates iron deficiency:

• Low serum iron (72 μg/dL) combined with elevated TIBC (475 μg/dL) indicates depleted iron stores, as TIBC rises when iron availability is low 1
• Transferrin saturation of 15% confirms iron-deficient erythropoiesis, as values <16% in adults are diagnostic of iron deficiency 1
• The pattern of low iron, high TIBC, and low transferrin saturation is the classic triad for absolute iron deficiency 1

Important caveat: While serum ferritin is the single most useful marker for iron deficiency, your transferrin saturation and TIBC pattern strongly support the diagnosis even without ferritin results 1. However, if ferritin was measured and is normal or elevated, consider that inflammation from your recent leukocytosis could mask iron deficiency, as ferritin is an acute-phase reactant 1.

Immediate Treatment Recommendation

Begin oral iron therapy with ferrous sulfate 324 mg (65 mg elemental iron) once daily 2:

• This provides 362% of the recommended daily intake and is the most cost-effective first-line treatment 2, 3
• Expect a hemoglobin rise of ≥10 g/L within 2 weeks if true iron deficiency is present 1
• A good response to iron therapy is highly suggestive of absolute iron deficiency, even when iron studies are equivocal 1

If hemoglobin does not increase by 1-2 g/dL within one month, consider: 4

• Malabsorption of oral iron
• Ongoing blood loss
• Incorrect diagnosis
• Need for intravenous iron therapy

Investigation for Underlying Cause

You require gastrointestinal investigation to identify the source of iron deficiency, as approximately one-third of adults with unexplained iron deficiency have underlying GI pathology, including malignancy 1:

Essential Initial Workup:

• Urinalysis or urine microscopy to exclude urinary blood loss 1
• Celiac disease screening (tissue transglutaminase antibodies), as celiac disease is found in 3-5% of iron deficiency cases 1
• Detailed history focusing on: 1
  • Gastrointestinal symptoms (abdominal pain, change in bowel habits, melena, hematochezia)
  • Dietary intake and malabsorption symptoms
  • Medication use (NSAIDs, anticoagulants, aspirin)
  • Family history of GI malignancy or inflammatory bowel disease
  • For women: menstrual history

Endoscopic Evaluation:

Bidirectional endoscopy (gastroscopy and colonoscopy) should be performed as first-line GI investigation, particularly given: 1, 2

• Your confirmed iron deficiency
• Recent leukocytosis (which may indicate inflammation or occult pathology)
• The need to exclude GI malignancy, which can present with iron deficiency even without overt symptoms 1

Age, sex, hemoglobin level, and mean cell volume are independent predictors of GI cancer risk and must be considered in your holistic risk assessment 1. While you haven't provided these details, any adult with unexplained iron deficiency warrants urgent GI evaluation 1.

Special Consideration: Leukocytosis Context

The recent leukocytosis you mentioned raises important considerations:

• Inflammation can falsely normalize ferritin levels while true iron deficiency exists 1
• If ferritin is between 15-150 μg/L in the setting of inflammation, iron deficiency may still be present 1
• Transferrin saturation becomes particularly valuable when inflammation is suspected, as it helps distinguish true iron deficiency from anemia of chronic disease 1
• Consider inflammatory bowel disease, chronic infection, or malignancy as potential causes linking both the leukocytosis and iron deficiency 1

Monitoring and Follow-up

• Recheck hemoglobin in 2-4 weeks to confirm response to oral iron 1, 4
• Continue iron supplementation for 3-6 months after hemoglobin normalizes to replenish iron stores 3
• If inadequate response or recurrent iron deficiency occurs, proceed with small bowel evaluation (capsule endoscopy) after negative bidirectional endoscopy 1

Critical pitfall to avoid: Do not delay investigation while treating with iron, as this may mask an underlying malignancy temporarily while allowing disease progression 1.