Fluid balance

Fluid balance is a critical aspect of the body's homeostasis. It involves maintaining the volume and composition of body fluid within normal ranges. An imbalance in fluid balance can lead to dehydration, overhydration, or electrolyte imbalances.

Overview

Body fluids can be discussed in terms of two compartments: the intracellular fluid (ICF) and the extracellular fluid (ECF). The ICF makes up about two-thirds of the total body water. The ECF, which makes up the remaining one-third, can be further divided into the interstitial fluid, plasma, lymph, cerebrospinal fluid, and transcellular fluid.

Regulation of Fluid Balance

The body maintains fluid balance by adjusting the intake and output of water and electrolytes. The primary organs involved in this process are the kidneys. They filter out wastes while returning needed substances to the blood. Their functioning is influenced by several hormones, including antidiuretic hormone (ADH), aldosterone, and atrial natriuretic peptide (ANP).

Disorders of Fluid Balance

Disorders of fluid balance can involve either volume imbalances, such as dehydration and overhydration, or electrolyte imbalances. Electrolyte imbalances can occur with levels of sodium, potassium, and other electrolytes either too high (hyper-) or too low (hypo-).

See Also

• Dehydration
• Overhydration
• Electrolyte imbalance
• Kidney function