Colloid Osmotic Pressure Calculator

Determines the pressure induced by proteins in blood plasma that tends to pull fluid into the capillaries.

Refer to the text below the tool for more information on this type of pressure.


Colloid osmotic pressure is also called oncotic pressure and in plasma is about 0.5% of the total osmotic pressure. The large majority of COP in capillaries (appx 80%) of the total oncotic pressure exerted by blood plasma on interstitial fluid is generated by albumin.

Plasma colloid osmotic pressure is an important determinant in the appearance of edema and in critically ill patients, a reliable predictor of survival.


Colloid Osmotic Pressure (COP) = (Globulin in g/dL x 1.4) + (Albumin in g/dL x 5.5)

Parameter Normal Low Normal High
Globulin 2 g/dL (20 g/L) 3.5 g/dL (35 g/L)
Albumin 3.4 g/dL (34 g/L) 5.4 g/dL (54 g/L)
Colloid Osmotic Pressure (COP) 23 mmHg 29 mmHg

Globulin
Albumin
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Colloid Osmotic Pressure Explained

In normal plasma, the proteins are the major colloids present and as the colloids are solutes, they contribute to the total osmotic pressure of the solution. Colloid osmotic pressure is also called oncotic pressure and in plasma is about 0.5% of the total osmotic pressure.

The large majority of COP in capillaries (appx 80%) of the total oncotic pressure exerted by blood plasma on interstitial fluid is generated by albumin.

Colloid Osmotic Pressure = (Globulin in g/dL x 1.4) + (Albumin in g/dL x 5.5)

COP has the opposing effect of hydrostatic blood pressure (drawing molecules into the interstitial spaces) and interstitial colloidal osmotic pressure.

In a steady state the measured colloid osmotic pressure replicates the value computed from serum proteins and in healthy individuals it averages 25.4 mmHg. It tends to decrease with age and is lower in females and during extended bed rest.

Reference ranges

Parameter Normal Low Normal High
Globulin 2 g/dL (20 g/L) 3.5 g/dL (35 g/L)
Albumin 3.4 g/dL (34 g/L) 5.4 g/dL (54 g/L)
Colloid Osmotic Pressure (COP) 23 mmHg 29 mmHg

Plasma colloid osmotic pressure is an important determinant in the appearance of edema and in critically ill patients, a reliable predictor of survival. In conditions where plasma proteins are reduced, for example proteinuria, there will be a reduction in oncotic pressure and an increase in filtration across the capillary, resulting in edema.

 

References

Ingerslev P, Larsen OA, Lassen NA. Measurement of the colloid osmotic pressure in serum with Tybjaerg Hansen's osmometer. Scand J Clin Lab Invest. 1966; 18(4):431–436.

Webber CE, Garnett ES. The relationship between colloid osmotic pressure and plasma proteins during and after cardiopulmonary bypass. J Thorac Cardiovasc Surg. 1973; 65(2):234–237.


Specialty: Hematology

Abbreviation: COP

Article By: Denise Nedea

Published On: June 15, 2020

Last Checked: June 15, 2020

Next Review: June 15, 2025