Nurses and health care professionals are involved continually in the assessment of fluid and electrolyte imbalance. Medical advances and new treatment modalities have increased the importance of a strong background in the physiologic concepts associated with these imbalances. Additionally, the expanded role of nurses in the community requires them to function more autonomously in assisting patients to control fluid and electrolyte imbalances. Every seriously or chronically ill person is likely to develop one or more of these imbalances, and the very young and the very old are especially vulnerable to changes in fluid and electrolyte balance. Even those who are only moderately ill are at high risk for these imbalances. Multiple health care providers are responsible for maintaining homeostasis of fluid and electrolyte balance when caring for patients. After completing this book, the learner should understand more fully the effects of fluid, electrolyte, and acid-base balance and imbalance on the body as they occur in many clinical health problems across the life span.