Progressive Care Nursing Certification (PCCN) Practice Exam

What characterizes the oliguric phase of acute tubular necrosis (ATN)?

1. Decreased UO, hypokalemia, alkalosis, elevated creatinine

2. Decreased UO, hyperphosphatemia, acidosis, hyponatremia

3. Hypotension, acidosis, elevated BUN, hypernatremia

4. Hypertension, alkalosis, elevated creatinine, hypercalcemia

The correct answer is: Decreased UO, hyperphosphatemia, acidosis, hyponatremia

The oliguric phase of acute tubular necrosis (ATN) is marked by a significant decrease in urine output, often leading to fluid overload and subsequent electrolyte imbalances. This phase typically features alterations in various metabolic parameters due to the kidneys' reduced ability to excrete waste and maintain homeostasis. The decrease in urine output, or oliguria, is a key characteristic of this phase. The buildup of phosphorus results in hyperphosphatemia since the kidneys are unable to excrete it properly. Alongside this, acidosis occurs due to the retention of hydrogen ions and the failure to excrete acids effectively, leading to metabolic acidosis. Additionally, the improper regulation of sodium can lead to hyponatremia, where sodium levels in the blood become lower than normal. This combination of decreased urine output, hyperphosphatemia, acidosis, and hyponatremia highlights the dysfunction of the renal system during the oliguric phase of ATN, which is distinct from other phases or conditions that may exhibit different clinical or biochemical profiles.