Challenges and Pitfalls When Measuring Malabsorption in Hospitalized Patients with Haematologic Malignancies

Background & Aims: High dose chemotherapy-or graft versus host disease-induced gastro-intestinal mucositis occurs in 90% of the patients undergoing allogeneic HCT, with watery diarrhea as one of the key symptoms.Several methods are available to objectify and quantify malabsorption or impaired intestinal function, but not validated in patients with haematological malignancies.We set up a study to investigate whether these gold standard methods are valid markers for detecting malabsorption and applicable in clinical practice.Unfortunately, it appeared unfeasible in this patient group.This manuscript therefore addresses the challenges and pitfalls of this observational study.Methods: The study had a cross sectional and observational study design, aiming to include 45 adult patients with hematological malignancies with chemotherapy-or GVHD-induced-mucositis and severe diarrhea.To assess intestinal function and quantify malabsorption, patients undergo a citrulline generation test and 72-hour collection of feces in pre-weighted bucket combined with 96-hour actual registration and calculation of nutritional intake.Results: During 21 months study period 12/71 (17%) of patients who fulfilled inclusion, criteria were included, of which 10 of them were male and all participants had chemotherapyinduced-mucositis.Main reason for not participating was patients feeling too ill to collect feces.Only 3 patients were tested according to the research protocol.Conclusion: Measuring intestinal function using gold standard is unfeasible in practice in this patient group.It is important to be aware that, although firm conclusions cannot be drawn, severe treatment-related diarrhea may be accompanied by malabsorption and this should be allocated in treatment protocols so that risks in nutritional-and/or hydration status can be monitored and anticipated if necessary.