Blood test results of children being treated for leukemia often fluctuate wildly. WBCs can go down to zero or be above normal. RBCs may go down periodically during treatment, necessitating transfusions of packed red cells. Platelet levels may also decrease, sometimes requiring platelet transfusions. Absolute neutrophil counts (ANC) are closely watched, as they give the oncologist an idea of the child’s ability to fight infections; ANCs range from zero into the thousands. Chemotherapy can also cause changes in kidney and liver function, along with changes in electrolytes and mineral levels in the blood.

Pediatric oncologists consider all of the blood test results to get the total picture of a child’s reaction to illness, treatment, or infection. Trends are more important than any single value.