Fluidvolumen

Fluidvolumen is a biomedical term that refers to the total amount of body fluids and their distribution among bodily compartments. It encompasses intracellular fluid (ICF) and extracellular fluid (ECF), the latter including interstitial fluid and intravascular fluid (plasma). Fluidvolumen is a dynamic parameter that changes with intake and losses, as well as shifts between compartments driven by hormonal regulation and disease processes.

In adults, total body water accounts for roughly 50–60% of body weight. The extracellular compartment represents about 20% of body weight, with plasma volume around 4–5% and interstitial fluid making up the remainder of the extracellular space. These values vary with age, sex, body composition, and health status. Fluidvolumen is influenced by osmotic forces and hydrostatic pressures, and is tightly regulated by mechanisms such as thirst, antidiuretic hormone, the renin-angiotensin-aldosterone system, and natriuretic peptides.

Clinical assessment of fluidvolumen combines physical examination, weight monitoring, and laboratory markers. Signs of hypovolemia or dehydration include low skin turgor and tachycardia, while hypervolemia can cause edema and elevated venous pressures. Laboratory approaches range from routine tests (hematocrit, serum osmolality, albumin) to more advanced methods such as isotope or dye dilution, and bioelectrical impedance analysis to estimate total body water and its compartments. In critical care and perioperative settings, maintaining appropriate intravascular volume and avoiding edema are central goals of fluid management, guided by the patient’s response to therapy and fluid balance data.

Disorders of fluidvolumen occur with dehydration, fluid overload, and redistribution in conditions such as heart failure, kidney disease, liver disease, and sepsis.