Manitoba Nephrology Nurse Practice Test

Fluid retention due to poor kidney excretion is the physiological mechanism behind edema in patients with kidney disease. When the kidneys are compromised, their ability to filter and excrete excess fluids and waste products is diminished. This leads to an accumulation of fluid in the body, resulting in edema, particularly in the extremities and areas such as the abdomen.

In normally functioning kidneys, water and sodium balance is tightly regulated. When kidney function declines, there is a decreased ability to remove excess sodium and fluid, leading to an increase in blood volume. The retention of sodium contributes to further water retention, exacerbating the problem. This overloaded fluid volume can spill over into interstitial tissues, producing the observable swelling characteristic of edema.

Other factors such as excessive exercise or increased dietary salt intake can also influence fluid balance, but they are not the primary mechanisms responsible for edema in kidney disease. While these factors can contribute to fluid retention under certain circumstances, the fundamental issue in kidney disease is the kidneys' impaired ability to excrete fluids adequately.