How do you approach IVIG replacement for pediatric patients with low IgG during treatment for hematologic malignancies?

We monitor IgG levels at the beginning of each chemotherapy cycle for infants, for patients with Down syndrome, for those receiving blinatumomab, and for patients who are hypogammaglobulinemic with recurrent bacterial infections, and we replace when IgG levels are <400 mg/DL for down syndrome and <5...