A 37-yr-old female patient is hospitalized with acute kidney injury (AKI). Which information will be most useful to the nurse in evaluating improvement in kidney function?

A. Glomerular filtration rate (GFR): GFR is the most direct indicator of overall kidney function because it reflects the rate at which the kidneys filter blood and clear waste products. In acute kidney injury, improvement is best demonstrated by a rising GFR toward baseline values, indicating recovery of nephron function and improved filtration capacity. B. Potassium level: Serum potassium levels are important to monitor because hyperkalemia is a life-threatening complication of AKI. However, potassium can fluctuate due to medications, diet, or temporary shifts between intracellular and extracellular compartments, making it less specific for evaluating true renal recovery. C. Blood urea nitrogen (BUN) level: BUN is commonly elevated in AKI due to reduced excretion of nitrogenous waste. However, BUN can also be influenced by hydration status, protein intake, and catabolic states, limiting its reliability as a sole marker of improving kidney function. D. Urine volume: Increased urine output may suggest improvement, particularly during the recovery phase of AKI. However, urine volume alone does not necessarily reflect adequate filtration, as patients may produce urine without effectively clearing solutes. Filtration capacity is more accurately assessed by GFR.