Onkotischer

Onkotischer is an adjective used in physiology and medicine to describe properties related to the colloid osmotic pressure of plasma, the component of osmotic pressure contributed by circulating plasma proteins. In English, the corresponding term is oncotic, and in German it is commonly applied to phrases such as onkotischer Druck or onkotische Prozesse.

Colloid osmotic (oncotic) pressure is generated mainly by plasma proteins, especially albumin, which are too large to pass freely through the capillary wall. This pressure helps retain fluid within the vascular compartment and opposes capillary hydrostatic pressure, influencing fluid exchange at the capillary level. The balance of these forces, often described by Starling principles, governs filtration and reabsorption across capillaries.

Clinically, alterations in oncotic pressure can affect fluid distribution. Hypoalbuminemia, as seen in liver disease, nephrotic syndrome, malnutrition, or severe inflammation, lowers plasma oncotic pressure and can contribute to interstitial edema. Conversely, therapies that raise oncotic pressure, such as albumin administration, may be used in certain forms of shock or severe hypoalbuminemia to support intravascular volume. The concept is also important in understanding fluid shifts during critical illness and in monitoring conditions that influence protein synthesis or loss.

The term onkotischer is primarily used in German-language medical literature to denote things related to oncotic pressure. In English-language texts, the equivalent term oncotic is used, often in the context of colloid osmotic pressure and its physiological or clinical implications.