Metabolic consequences following colonic resection in patients with Familial Adenomatous Polyposis [FAP]

Abstract

Introduction: The colon is an active metabolic organ, and its removal leads to sodium depletion, chronic activation of the renin-angiotensin-aldosterone system (RAAS), hyperaldosteronism and abnormal glucose tolerance. Previous work has studied patients who have undergone colectomy for inflammatory bowel disease (IBD), so results may be confounded by the effects of inflammation and/or prior medication use. Patients with familial adenomatous polyposis (FAP) undergo prophylactic colectomy with ileorectal anastomosis (IRA), restorative proctocolectomy (RPC) or proctocolectomy with end-ileostomy (PPC), usually in their late teens. These patients do not have IBD and are usually not on medication, thus providing a better group to study. Aims: The aim of the work in this thesis was to determine the prevalence of metabolic disturbances following colectomy in patients with FAP, and to evaluate the efficacy of oral rehydration therapy (ORT) in correcting and preventing these metabolic disturbances. Methods: This thesis comprises three clinical studies of patients with FAP who had undergone colectomy, using validated questionnaires and diaries (food and bowel habit symptom diaries), clinical and biochemical data (one observational study and two single-blinded, placebo-controlled randomised trials). This thesis also describes the immunohistochemistry findings related to small intestinal adaptation following colectomy. Findings: Nearly half of our patients (47%) demonstrated activation of RAAS post colectomy with increased plasma aldosterone values, a state of dehydration and poor quality of life. ORT reversed these metabolic disturbances leading to a positive impact on the quality of life. Incorporating ORT in the standard post-operative care plan resulted in prevention of RAAS activation. Conclusions: Metabolic disturbances are common following colectomy. ORT forms a safe, efficient and cost-effective treatment strategy to restore the metabolic homeostasis and also prevent metabolic disturbances if incorporated from the immediate post-operative period.Open Acces