What is the workup for a patient with iron deficiency anemia and decreased Partial Thromboplastin Time (PTT)?

Workup for Iron Deficiency Anemia with Decreased PTT

A patient with iron deficiency anemia and decreased PTT requires a comprehensive GI evaluation including upper endoscopy, colonoscopy, and small bowel assessment to identify the source of blood loss, along with coagulation studies to evaluate for potential hypercoagulable conditions. 1

Initial Diagnostic Approach

Laboratory Assessment

• Complete blood count with peripheral smear
• Comprehensive iron studies:
  • Serum ferritin (diagnostic thresholds 1:
    • <30 μg/L: Definitive iron deficiency
    • 30-100 μg/L with transferrin saturation <20%: Possible iron deficiency, especially with inflammation

    • 100 μg/L with normal transferrin saturation: Iron deficiency unlikely

  • Transferrin saturation (target ≥20%)
  • Total iron binding capacity
• Comprehensive coagulation panel:
  • PTT (already known to be decreased)
  • PT/INR
  • Specific factor assays (particularly factors VIII, IX, XI, XII)
  • von Willebrand factor levels and activity

Gastrointestinal Evaluation

• Upper GI endoscopy with small bowel biopsies (to rule out celiac disease)
• Colonoscopy or double contrast barium enema
• Consider small bowel evaluation in transfusion-dependent cases 1

Specific Considerations for Decreased PTT

A decreased PTT is uncommon and warrants special attention as it may indicate:

• Elevated levels of coagulation factors (particularly factor VIII)
• Potential hypercoagulable state
• Possible association with inflammatory conditions

Additional Testing Based on Initial Findings

• If GI evaluation is negative:

  • Consider gynecological causes in women (heavy menstrual bleeding)
  • Evaluate for malabsorption (celiac panel, fecal fat)
  • Consider rare causes (intravascular hemolysis, paroxysmal nocturnal hemoglobinuria)

• If coagulation abnormalities persist:

  • Thrombophilia workup
  • Lupus anticoagulant
  • Factor VIII activity levels

Treatment Considerations

While completing the diagnostic workup, initiate treatment for iron deficiency anemia:

• First-line: Oral iron supplementation

  • Ferrous sulfate 324 mg (65 mg elemental iron) once daily 1
  • Consider alternate-day dosing for improved tolerability
  • Take on empty stomach with vitamin C (500 mg) to enhance absorption
  • Avoid calcium-containing foods, tea, coffee, or antacids

• Consider IV iron if 1:

  • Hemoglobin <10 g/dL
  • Intolerance to oral iron
  • Inflammatory bowel disease or other active inflammatory conditions
  • Poor response to oral therapy (<1.0 g/dL increase in hemoglobin after 14 days) 2

Monitoring Response

• Check hemoglobin after 2-4 weeks of therapy 1
• Consider expedited IV iron if hemoglobin increase is <1.0 g/dL at day 14 1, 2
• Continue monitoring every 4 weeks until hemoglobin normalizes 1
• Continue oral iron for 3 months after hemoglobin normalizes to replenish stores 1

Common Pitfalls to Avoid

• Accepting upper GI findings as the sole cause without lower GI evaluation (dual pathology occurs in 10-15% of patients) 1
• Overlooking occult GI blood loss in men and postmenopausal women 1
• Premature discontinuation of iron supplementation before iron stores are replenished 1
• Using inappropriate ferritin cutoffs for diagnosis, especially in inflammatory conditions 1
• Failing to investigate decreased PTT, which may indicate a hypercoagulable state requiring specific management
• Neglecting to consider the impact of acid-suppressing medications (e.g., omeprazole) on iron absorption 3

Remember that iron deficiency anemia in men and postmenopausal women almost always indicates blood loss, most commonly from the gastrointestinal tract, and requires thorough investigation to identify the underlying cause 1, 4.