Oral Rehydration Therapy

Oral rehydration therapy Author: Stephen Freedman, MDCM, MSc Section Editors: Tej K Mattoo, MD, DCH, FRCP Anne M Stack, MD Deputy Editor: Melanie S Kim, MD Contributor Disclosures All topics are updated as new evidence becomes available and our peer review process is complete. Literature review current through: Jan 2017. | This topic last updated: Jan 25, 2017. INTRODUCTION — Globally, diarrheal disease remains one of the leading causes of childhood mortality and morbidity. Loss of intestinal fluid caused by gastroenteritis may lead to severe hypovolemia, shock, and death, particularly in children younger than five years of age in areas of the world with limited resources. In developed countries, such as the United States, diarrhea caused by gastroenteritis remains a major cause of hospitalizations. (See "Approach to the child with acute diarrhea in resource-limited countries".) Although the total number of deaths globally from diarrheal diseases from gastroenteritis remains high, the overall mortality rate has steadily declined over the last few decades. This decline, especially in developing countries, is largely due to the use of early and appropriate oral rehydration therapy (ORT), improved nutrition and water sanitation measures, and effective vaccination for rotavirus. (See "Approach to the child with acute diarrhea in resource-limited countries", section on 'Prevention'.) The composition of oral rehydration solutions and the clinical application of ORT in patients with diarrhea due to gastroenteritis are discussed in this topic review. The assessment and treatment of hypovolemia, and prevention and treatment of viral gastroenteritis in children are discussed separately. (See "Clinical assessment and diagnosis of hypovolemia (dehydration) in children" and "Treatment of hypovolemia (dehydration) in children" and "Acute viral gastroenteritis in children in resource-rich countries: Management and prevention".) DEFINITIONS OF HYPOVOLEMIA AND DEHYDRATION — The terms volume depletion (hypovolemia) and dehydration often are used interchangeably. However, these terms differentiate physiologic conditions resulting from different types of fluid loss. Much of the clinical literature does not differentiate between the two terms and uses them interchangeably. Thus, we will follow this convention and use the terms hypovolemia, volume depletion, and dehydration interchangeably as referring to all types of fluid deficits. (See "General principles of disorders of water balance (hyponatremia and hypernatremia) and sodium balance (hypovolemia and edema)".)

BACKGROUND — Although oral rehydration therapy (ORT) was first introduced in 1945, its use declined because of reports of multiple cases of hypernatremia due to the use of oral rehydration solution (ORS) with inappropriately high carbohydrate levels [1]. However, the success of intravenous (IV) hydration in decreasing mortality and morbidity in children with diarrhea in developing countries led to renewed efforts in the 1960s to develop an effective ORT that would be less expensive and easier to administer [2,3]. Subsequently, improvements in ORS formulations have led to ORT's successful use in treating hypovolemia caused by gastroenteritis [4-6]. (See 'Efficacy' below.) Physiologic basis Water absorption — The following three principal mechanisms are responsible for passive intestinal water absorption (see "Pathogenesis of acute diarrhea in children", section on 'Water absorption'): ●Sodium/hydrogen (Na/H) exchangers ●Electrochemical gradient ●Sodium-coupled transport with carrier organic solutes (eg, glucose) Disruption of any of the above processes can result in diarrhea. However, in children with diarrhea due to gastroenteritis, the sodium-coupled co-transport with glucose and other carrier organic solutes remains intact [7,8]. ORS properties — ORT is based on the preserved co-transport of glucose and sodium in patients with diarrhea due to gastroenteritis. Studies from the 1960s showed an ORS formulation that is isotonic with equimolar concentrations of glucose and sodium is as effective as IV hydration in treating hypovolemia in patients with cholera [7,8]. Subsequent formulations are based on this initial formulation (table 1). The following properties for ORS are recommended by the World Health Organization (WHO) [9]: ●Total osmolality between 200 and 310 mOsm/L ●Equimolar concentrations of glucose and sodium ●Glucose concentration