What labs would you order for a 3-year-old with easy bruising and suspected iron deficiency anemia?

Laboratory Evaluation for a 3-Year-Old with Easy Bruising and Suspected Iron Deficiency Anemia

For a 3-year-old with easy bruising and suspected iron deficiency anemia, you should order a complete blood count (CBC), iron studies (serum ferritin, iron, TIBC, transferrin saturation), and coagulation studies (PT, PTT, platelet function). This comprehensive approach addresses both the potential iron deficiency and bleeding disorder concerns that could explain the child's symptoms.

Initial Laboratory Evaluation

For Iron Deficiency Assessment:

• Complete Blood Count (CBC) with differential
  • Hemoglobin and hematocrit levels
  • Red cell indices (especially MCV)
  • Red cell distribution width (RDW)
• Iron Studies:
  • Serum ferritin (most specific indicator of depleted iron stores)
  • Serum iron
  • Total iron binding capacity (TIBC)
  • Transferrin saturation

For Bleeding Disorder Assessment:

• Platelet count (part of CBC)
• Coagulation studies:
  • Prothrombin time (PT)
  • Partial thromboplastin time (PTT)
  • Platelet function study
  • Von Willebrand screen

Rationale for Testing

The dual approach is necessary because:

1. Iron deficiency is common in children: Iron deficiency anemia is the most common hematologic disorder in children 1, 2, and screening is recommended for at-risk children aged 2-5 years 3.

2. Easy bruising warrants bleeding disorder evaluation: The combination of easy bruising and suspected anemia requires investigation for potential bleeding disorders 3. The hematology guidelines recommend that if easy bruising is present, screening should include CBC, platelet count, platelet function study, and von Willebrand screen 3.

3. Differential diagnosis is important: While iron deficiency is common, easy bruising may indicate a separate or additional condition like von Willebrand disease or thrombocytopenia 3.

Interpretation of Results

• Microcytic anemia (low MCV) with elevated RDW: Suggests iron deficiency anemia 3, 2
• Low ferritin (≤15 μg/L): Confirms iron deficiency 3
• Abnormal coagulation studies: May indicate a bleeding disorder requiring hematology referral 3

Management Based on Results

• If iron deficiency is confirmed:

  • Prescribe 3 mg/kg/day of iron drops to be administered between meals 3
  • Counsel parents about dietary iron sources
  • Repeat hemoglobin/hematocrit in 4 weeks to confirm response (increase in Hb ≥1 g/dL confirms iron deficiency anemia) 3

• If coagulation abnormalities are found:

  • Refer to pediatric hematology for further evaluation 3

Important Considerations

• Easy bruising in children can be caused by both iron deficiency and bleeding disorders, so both must be evaluated 3
• Dietary history is important - excessive milk intake (>24 oz daily) is a risk factor for iron deficiency in children aged 1-5 years 3
• If initial testing suggests a bleeding disorder, further specialized testing may be required under hematology guidance 3
• A normal CBC does not exclude iron deficiency without anemia, which can still have developmental consequences 4

This approach ensures that both the suspected iron deficiency and the concerning easy bruising are properly evaluated, allowing for appropriate treatment to address the underlying cause(s) of the child's symptoms.