What would you do if a postmenopausal woman with iron deficiency anemia (IDA) has thrombocytopenia and a negative colonoscopy?

Management of Postmenopausal Woman with Iron Deficiency Anemia, Mild Thrombocytopenia, and Negative Colonoscopy

In a postmenopausal woman with iron deficiency anemia (IDA), mild thrombocytopenia (platelets 120-150), and a negative colonoscopy, I recommend proceeding with gastroscopy and small bowel evaluation via capsule endoscopy to identify the source of blood loss, while simultaneously initiating iron replacement therapy. 1, 2

Diagnostic Approach

Initial Assessment

• The combination of IDA and mild thrombocytopenia requires thorough investigation, as this may represent a more severe iron deficiency state 3, 4
• Mild thrombocytopenia (120-150) can be associated with iron deficiency and typically resolves with iron replacement 3
• A negative colonoscopy eliminates one potential source but does not complete the evaluation

Recommended Diagnostic Algorithm:

1. Upper GI Endoscopy (Gastroscopy) - Must be performed even with negative colonoscopy 1, 2

   • Evaluates for gastric/duodenal ulcers, gastritis, malignancy, and celiac disease
   • Include duodenal biopsies to screen for celiac disease (found in 3-5% of IDA cases) 1

2. Laboratory Testing:

   • Confirm iron deficiency with complete iron studies (ferritin, transferrin saturation, TIBC) 2
   • Check inflammatory markers (CRP/ESR) as inflammation can mask iron deficiency 2
   • Screen for celiac disease with transglutaminase antibodies (if not done via biopsy) 1
   • Urinalysis to evaluate for hematuria 1

3. Small Bowel Evaluation if gastroscopy is negative:

   • Capsule endoscopy is the preferred method for small bowel examination in IDA 1
   • Should be considered especially with concurrent thrombocytopenia, which may indicate more severe blood loss 3

Treatment Approach

Iron Replacement Therapy

• Start immediately - Do not defer iron therapy while awaiting further investigations 1, 2
• Oral iron: One tablet daily of ferrous sulfate, fumarate or gluconate 1
  • Take with vitamin C (250-500mg) to enhance absorption 2
  • If not tolerated, consider alternate-day dosing or parenteral iron 1, 2
• Monitor response: Expect hemoglobin rise ≥10 g/L within 2 weeks 1
  • A good response confirms iron deficiency even if iron studies are equivocal
  • Continue treatment for 3 months after hemoglobin normalization 1, 2

Management of Thrombocytopenia

• Mild thrombocytopenia (120-150) in this context is likely due to iron deficiency 3, 4
• Iron replacement alone should improve platelet counts without specific platelet-directed therapy 3
• Monitor platelet counts along with hemoglobin during iron therapy

Follow-up Plan

1. Check hemoglobin and platelet response at 2-4 weeks 1, 2
2. If inadequate response to oral iron or worsening thrombocytopenia:
   • Consider switching to IV iron 2
   • Expedite any pending investigations
3. After normalization of hemoglobin and platelets:
   • Continue iron for additional 3 months to replenish stores 1, 2
   • Monitor every 3 months for 12 months, then every 6 months for 2-3 years 2

Important Considerations

• The combination of IDA and thrombocytopenia increases the likelihood of significant underlying pathology 3, 4
• Dual pathology (significant causes in both upper and lower GI tracts) may occur in 1-10% of patients 1
• If all investigations are negative and anemia persists or recurs despite adequate iron therapy, consider hematology consultation to evaluate for other bone marrow disorders

Pitfalls to Avoid

• Do not stop at negative colonoscopy - upper GI and small bowel sources are common in postmenopausal women 1
• Do not delay iron replacement while awaiting further investigations 1
• Do not attribute mild thrombocytopenia to an unrelated cause - it is likely connected to the iron deficiency 3, 4
• Do not forget to screen for celiac disease, which is present in 3-5% of IDA cases 1