Materials and Methods
We performed a single institution, IRB approved, retrospective study to quantify and characterize the rate of “shunters” treated in our center. Expert chart review by the authors was conducted on each eligible patient. Patients were included in our cohort if they were aged 0-30 years and treated for B cell or T cell ALL or lymphoblastic lymphoma (LL) at our institution over a 10-year period from January 1, 2009 to June 1, 2019. Additional inclusion criteria included receiving maintenance therapy at our institution for at least a 12-month period. All of those treated for less than 12 months were excluded from data collection and analysis. Clinical demographics including age, gender, ethnicity, disease type, risk stratification, and treatment protocol were collected. Incidents of hypoglycemia (glucose <74 mg/dL), hepatic inflammation (Alanine aminotransferase [ALT] >123 U/L), pancreatitis (amylase >100 U/L or lipase >60 U/L), and hypogammaglobulinemia (IgG <400 mg/dL) were recorded. We queried the treatment records for the maximum dose of 6-MP prescribed during maintenance therapy, identifying if an individual had their 6-MP dosing increased above 100%. If available, thiopurine metabolite levels were recorded, noting levels of 6-MMPN greater than 10 000 pmol/8 x 108 RBC. We defined “shunters” as individuals who had 6-MMPN levels greater than 10 000 pmol/8 x 108 RBC. If a patient was started on allopurinol, we noted the dose(s) of allopurinol at the start of therapy and throughout the treatment course, the effects of the allopurinol intervention on the aforementioned lab values, and the patient’s clinical course. Descriptive statistics were calculated in Stata ver. 16.