3 Introduction

Protein-energy malnutrition (PEM) is not limited to the severe cases seen in developing countries. Individuals with varying degrees of malnutrition are seen in both inpatient and outpatient settings in the U.S., and all ages may be affected. By definition, PEM results from inadequate intakes of protein, energy fuels, or both. Deficiencies of protein and energy usually occur together but when one predominates and the deficit is severe, kwashiorkor (primarily protein deficiency) or marasmus (predominantly energy deficiency) ensues (Color Figure 63.1*). However, in many cases, it is difficult to recognize which deficit predominates.