2.3 Laboratory Findings and Classification

2.3.1 Hematology

2.3.1.1 Red Cells

• The level of hemoglobin may be normal, but more often moderate and sometimes markedly low

• Low number of reticulocytes

2.3.1.2 White Blood Cell Count

• Number of white blood cells can be normal, low, or high

• In children with leukopenia, few or no atypical lymphoblasts are detected

• In children with a high WBC, leukemic blast cells are present

• In children with a high WBC (more than 100 × 109 white blood cells/l), the lymphoblasts are predominant (together with marked visceromegaly)

2.3.1.3 Platelets

• The platelet count is usually low: in 50% of children, less than 50 × 109/l

•Spontaneous hemorrhage appears in children with less than 20–30 × 109 platelets/l, especially during febrile episodes

•The serum uric acid level is often high initially and during the first period of treatment (hyperuricemia)

•The serum potassium level may be high in patients with massive cell lysis (often together with hyperuricemia)