Adult-Gerontology Clinical Nurse Specialist (CNS) Practice Exam

Which electrolyte imbalance is least likely to be indicated in a patient with acute renal failure?

1. hyperkalemia

2. hypernatremia

3. metabolic acidosis

4. hypocalcemia

The correct answer is: metabolic acidosis

In patients with acute renal failure, the body's ability to excrete certain electrolytes is impaired, leading to various imbalances. Metabolic acidosis is a common complication of acute renal failure due to the kidneys' reduced capacity to excrete hydrogen ions and regenerate bicarbonate. This results in decreased serum bicarbonate levels and a buildup of acids in the body, often leading to a lower pH. In contrast, other electrolyte imbalances—such as hyperkalemia, hypernatremia, and hypocalcemia—are more directly associated with acute renal failure. Hyperkalemia occurs as a consequence of reduced renal clearance of potassium, which can lead to dangerous cardiac events. Hypernatremia may result from impaired urine concentration mechanisms or excessive sodium intake. Hypocalcemia can arise from acute kidney injury due to impaired conversion of vitamin D to its active form, which affects calcium absorption and regulation. Therefore, among these listed imbalances, metabolic acidosis is the one least likely to be indicated in a patient with acute renal failure, as it is almost expected due to the pathophysiological changes occurring in such conditions.