October 2006, Volume 36 Number 10 , p 70 - 71
GOERTZ, SHERRY RN, CNE, MSN
Sherry Goertz is a nursing instructor at the Mont Alto campus of Pennsylvania State University.
A MEASURE of the concentration of particles (such as electrolytes, urea, and glucose) in a solution, osmolality can help shed light on your patient's fluid balance. Water loss increases plasma osmolality; overhydration decreases it. Understanding osmosis, the process by which water moves into and out of cells, will help you grasp the significance of osmolality. (See Understanding osmosis. )
Normally, when fluid balance goes awry, the body restores homeostasis in one of two ways:
* Increased plasma osmolality triggers secretion of antidiuretic hormone (ADH), which causes the kidneys to reabsorb water and excrete more concentrated urine. The reabsorbed water dilutes the plasma, and plasma osmolality decreases. * Decreased plasma osmolality suppresses ADH secretion to reduce the amount of water the kidneys reabsorb. As a result, they pass more dilute ...