Movement of body fluids or transudation of body fluids:
Cell membranes are semi-permeable and will allow the transport of fluid and substances across the cell membrane. “Biomembranes are thin films consisting of proteins and lipid fats. They are not rigid or impermeable but, rather, are highly mobile and dynamic structures. Membranes act as the “gate-keepers” of the cell. They control not only access of inorganic ions, nutrients, and biological compounds, but also the entry of drugs and the exit of waste products.” Medical Biochemistry, Mosby, 1999, pg 69 ISBN 0-7234-3012-8
Generally speaking, a fluid shift towards increased ICW suggests anabolic processes and improved nutrient status. Contrarily, a shift towards increased ECW suggests a decline in health status of the patient.
Consider this quote from the textbook Medical Biochemistry: (Mosby, 1999, pgs 267-268 ISBN 0-7234-3012-8) “Under physiologic conditions, the average concentration of all osmotically active substances in the ECF is 290 mmol/kg H2O, and this remains in equilibrium with the ICF. A change in the concentration of osmotically active substances in either of the water compartments creates a gradient of osmotic pressure and, consequently, movement of water between compartments.”
Note: “Osmoltically active” means substances that can pass through the semi-permeable membrane of the cells of our body
Causes of Fluid Shift:
Electrolytes provide much of the osmotically active substances of both the ECF and the ICF. Sodium is the primary electrolyte of the ECF. Potassium is the primary electrolyte of the ICF. Magnesium is the key mineral responsible for triggering electrolyte pumping into and out of the cell. A deficiency in potassium or magnesium can cause a loss of ICW. An excess of sodium can cause an increase in ECW.
Toxicity: Toxins can increase the level of osmotically active substances and therefore cause an increase in the ECW. Patients with chronic heart failure and recent onset of peripheral edema had raised concentrations of endotoxin and plasma elevations of bacterial liopolysaccharides from the death of gram-negative bacteria. (Niebauer, J, Volk H-D, Kemp M, Dominguez M, et al. “Endotoxin and immune activation in chronic heart failure: a prospective cohort study.” Lancet. 1999; 353:1838-1842)
Mitochondrial Damage: The mitochondria is the “powerhouse” of the cell and provides energy to the rest of the body. The DNA of Mitochondria is at least 10 times more susceptible to oxidative damage than the DNA within the nucleus of the cell. Mitochondrial inefficiency due to oxidative damage and / or nutrient insufficiency can be a cause of fluid shift. (Richter C, Park JW, Ames BN. Normal oxidative damage to mitochondrial and nuclear DNA is extensive. Proc Natl Acad Sci USA. 1988;85:6465-6467.)
Stress: Sodium balance is regulated via the action of the adrenal hormone aldosterone on the kidneys. Therefore, stress, by means of its impact on adrenal function, can influence fluid balance. Certainly kidney function can also influence fluid balance.
Essential Fatty Acids: The integrity of the semi-permeable cell membrane is dependent upon the lipid content of the membrane. Low levels of the essential fatty acids, or high levels of artificial fats (trans fats) can have a negative impact on membrane integrity.
Inflammation: Inflammation due to trauma, toxicity or nutrient insufficiency can contribute to increases in extra-cellular fluid. Oxidant stress can damage cell membranes. High levels of glucose through the process of protein glycation can damage cell membrane proteins and impair the efficiency of active transport.
Chronic Disease: Disease processes associated with tissue catabolism can lead to a profound shift in body fluids. Cancer is an extreme example of a catabolic illness.
Allergies: Allergic responses increase the overall body level of histamine and cause a shift of fluid from inside the cell to outside of the cell.