What is the management approach for an 18-month-old child with a history of pallor and irregularity, presenting with shortness of breath and severe anemia (hemoglobin <70), normal white blood cell count, and potential need for tests such as Lactate Dehydrogenase (LDH), electrophoresis, and Coombs test?

Management of Severe Anemia in an 18-Month-Old with Suspected Hemolytic Anemia

Immediate Transfusion and Stabilization

This child requires immediate packed red blood cell transfusion given hemoglobin <70 g/L with respiratory symptoms, targeting an initial hemoglobin of 70-80 g/L. 1

• Transfuse 10-15 mL/kg of packed red blood cells immediately to address the critically low hemoglobin and shortness of breath 2, 1
• Each unit should increase hemoglobin by approximately 15 g/L in this age group 1
• Monitor continuously for cardiac decompensation, as severe anemia at this level carries extremely high risk 1
• Insert urinary catheter and target urine output >1 mL/kg/hour 1
• Provide supplemental oxygen to maximize oxygen delivery while anemia is being corrected 3

Essential Diagnostic Workup

Hemoglobin electrophoresis (Option B) is the single most critical test given the history of hand-foot syndrome in infancy, which strongly suggests sickle cell disease. 2, 4

The clinical presentation points toward hemolytic anemia requiring specific diagnostic tests:

Priority Testing (in order):

• Hemoglobin electrophoresis to diagnose sickle cell disease or other hemoglobinopathies, given the hand-foot syndrome history (dactylitis is pathognomonic for sickle cell disease in infancy) 2, 5
• Lactate dehydrogenase (LDH) - will be markedly elevated (often >1000 U/L) in hemolysis 1, 5
• Direct Coombs test (DAT) to differentiate immune from non-immune hemolysis 6, 5
• Reticulocyte count - should be >100 × 10⁹/L if bone marrow is responding appropriately to hemolysis 1, 5
• Indirect bilirubin and haptoglobin - indirect bilirubin will be elevated and haptoglobin will be decreased or undetectable in hemolysis 1, 6, 5
• Peripheral blood smear to identify sickle cells, spherocytes, schistocytes, or other abnormal morphologies 5

Additional Essential Tests:

• Glucose-6-phosphate dehydrogenase (G6PD) level to exclude enzymopathy 7, 5
• Blood culture as empiric broad-spectrum antibiotics (ceftriaxone 100 mg/kg/day) are warranted given risk of secondary bacterial infection in severe anemia 2

Specific Management Based on Likely Diagnosis

If Sickle Cell Disease (Most Likely):

• Initiate hydroxyurea therapy after acute crisis resolves, though severe anemia must be corrected before starting 6
• Provide aggressive hydration with maintenance fluids containing 5-10% glucose to prevent further sickling and hypoglycemia 2
• Monitor blood glucose closely as hypoglycemia is common in severe anemia 2
• Prophylactic folic acid supplementation is essential 2, 6

If Immune Hemolytic Anemia (Positive Coombs):

• Methylprednisolone 1-2 mg/kg/day should be initiated immediately 7
• Consider rituximab if corticosteroids are insufficient, though this is typically reserved for refractory cases 7
• Transfuse cautiously as alloimmunization risk is higher, but do not withhold transfusion when hemoglobin is this critically low 7

If Non-Immune Hemolysis (Negative Coombs):

• Investigate for membranopathies (hereditary spherocytosis), enzymopathies (G6PD deficiency, pyruvate kinase deficiency), or microangiopathic causes 5
• Even with negative DAT, if severe hemolysis is confirmed, consider corticosteroids combined with rituximab as this has been successful in DAT-negative hemolytic anemia 7

Critical Monitoring Parameters

• Check hemoglobin daily until stable above 70-80 g/L 1
• Monitor for signs of transfusion reactions or volume overload during blood product administration 1
• Serial electrolyte monitoring (potassium, calcium, magnesium, phosphate) as derangements are common and should be corrected per standard protocols 2
• Watch for hyperpyrexia which increases seizure risk - treat with ibuprofen (superior to paracetamol) with dose reduction if renal impairment develops 2

Common Pitfalls to Avoid

• Do not delay transfusion while awaiting diagnostic test results when hemoglobin is <70 g/L with symptoms 1, 8
• Do not use a liberal transfusion strategy targeting hemoglobin >100 g/L, as this increases transfusion requirements without improving outcomes 2, 1
• Do not assume negative Coombs test excludes immune hemolysis - DAT-negative hemolytic anemia exists and may still respond to immunosuppression 7
• Do not overlook the hand-foot syndrome history - this is highly specific for sickle cell disease and should drive immediate electrophoresis testing 2
• Minimize phlebotomy volume and frequency to prevent iatrogenic worsening of anemia 1