A nurse is caring for a school-age child who has acute renal failure. Which of the following findings should the nurse expect?

This question requires identifying the clinical manifestations of acute renal failure (ARF) in a child. Knowledge of the kidneys' role in fluid balance, electrolyte regulation, and acid-base homeostasis is necessary to predict expected laboratory and clinical findings. Choice A rationale . In acute renal failure, the kidneys are unable to excrete phosphorus, leading to hyperphosphatemia. Because phosphorus and calcium have an inverse relationship, the patient typically experiences hypocalcemia (normal range 8.5 to 10.5 mg/dL), not hypercalcemia. Choice B rationale . Oliguria, defined as urine output less than 0.5 to 1 mL/kg/hr, is a hallmark finding of acute renal failure. It results from a sudden decrease in the glomerular filtration rate and the kidneys' inability to filter waste products. Choice C rationale . The kidneys are the primary route for potassium excretion. In renal failure, potassium is retained, leading to life-threatening hyperkalemia (normal range 3.5 to 5.0 mEq/L). Hypokalemia is generally not expected unless there are significant extrarenal losses. Choice D rationale . The kidneys fail to excrete metabolic acids and cannot reabsorb bicarbonate effectively in ARF. This leads to metabolic acidosis, characterized by a low pH and low bicarbonate, rather than metabolic alkalosis, which involves a high pH..