What is the evaluation and management approach for a 22-month-old male with erythrocytosis (increased red blood cell count)?

From the Guidelines

The evaluation and management of a 22-month-old male with erythrocytosis should prioritize determining the underlying cause, with a focus on secondary causes such as cyanotic congenital heart disease, and managing symptoms to prevent complications like thrombosis, as recommended by the most recent guidelines 1. The initial assessment should include a complete blood count with differential, peripheral blood smear, reticulocyte count, iron studies, erythropoietin level, and oxygen saturation measurement. Key considerations in the evaluation process include:

• Determining whether the erythrocytosis is primary or secondary
• Investigating secondary causes such as cyanotic congenital heart disease, chronic lung disease, high altitude exposure, or certain kidney tumors that produce erythropoietin
• Considering genetic testing for JAK2 mutations or other congenital disorders like Chuvash polycythemia if primary erythrocytosis is suspected Management depends on the underlying cause but may include:
• Phlebotomy to maintain hematocrit below 45% if the child is symptomatic with headaches, dizziness, or thrombotic events, with the phlebotomy volume calculated based on the child's weight (typically 5-10 mL/kg) and performed with appropriate sedation and monitoring, as well as isovolumic fluid replacement 1
• Treating the underlying condition for secondary erythrocytosis
• Regular follow-up with a pediatric hematologist to monitor hematocrit levels, assess for complications like thrombosis, and adjust management accordingly It is essential to note that aspirin therapy is generally avoided in young children due to the risk of Reye syndrome unless specifically indicated for thrombotic risk 1. Therapeutic phlebotomy should only be performed in the presence of moderate/severe hyperviscosity symptoms due to secondary erythrocytosis (haematocrit > 65%) and in the absence of dehydration and iron deficiency, with isovolumic fluid replacement undertaken 1. Iron supplementation should be performed in the presence of iron deficiency (MCV < 80 fL) and carefully followed (rebound effect) 1.

From the Research

Evaluation Approach

The evaluation of a 22-month-old male with erythrocytosis involves several steps:

• Initial assessment to exclude polycythemia vera (PV) through JAK2 mutation screening 2
• Gathering of previous records on hematocrit (Hct) and hemoglobin (Hgb) levels to distinguish between longstanding and acquired erythrocytosis 2
• Measurement of serum erythropoietin (Epo) level to indicate primary or secondary cause 2, 3
• Germline mutation screening and review of historical data, including comorbid conditions and medication list 2

Diagnostic Considerations

Diagnostic considerations include:

• Hereditary erythrocytosis, especially with a positive family history 2, 4
• Acquired erythrocytosis due to central or peripheral hypoxia, Epo-producing tumors, or certain medications 2, 3
• Idiopathic erythrocytosis, which may be due to normal outliers or truncated diagnostic evaluation 2

Investigation

Investigation for the cause of erythrocytosis includes:

• Measurement of erythropoietin level to indicate primary or secondary cause 3, 5
• Mutational testing with PCR and NGS for suspected congenital causes 3
• Bone marrow biopsy, scans, and further investigation as indicated by history and initial findings 3, 6

Management

Management options include:

• Low-dose aspirin and venesection 6, 5
• Phlebotomy for symptom control, with frequency determined by symptoms rather than Hct level 2
• Cardiovascular risk optimization 2