Which laboratory findings would the nurse expect to see in a patient with acute kidney injury during the oliguric phase? (Select All that Apply.)

Rationale: A. Decreased serum creatinine is incorrect because during the oliguric phase of acute kidney injury (AKI), the kidneys’ ability to filter waste is impaired, causing creatinine to accumulate in the blood rather than decrease. Therefore, serum creatinine levels are elevated. B. Increased blood urea nitrogen (BUN) is correct. As kidney function declines, urea, a nitrogenous waste product, cannot be effectively excreted, leading to azotemia. Elevated BUN is a key indicator of decreased renal clearance during the oliguric phase. C. Decreased potassium is incorrect. The oliguric phase often leads to hyperkalemia, because potassium excretion by the kidneys is reduced. High serum potassium is a serious complication of AKI that can lead to cardiac dysrhythmias if not managed promptly. D. Increased glomerular filtration rate (GFR) is incorrect. The oliguric phase is characterized by reduced urine output, which reflects a decreased GFR. Kidney injury limits filtration, so GFR is low rather than high. E. Increased calcium is incorrect. AKI often causes hypocalcemia, not hypercalcemia. Phosphate retention in kidney injury leads to calcium binding and lower serum calcium levels. F. Increased serum creatinine is correct. Serum creatinine rises due to accumulation of nitrogenous waste that the kidneys cannot excrete efficiently. This is one of the hallmark laboratory findings of AKI in the oliguric phase. G. Decreased glomerular filtration rate (GFR) is correct. Reduced GFR occurs because of impaired renal perfusion and damage to the nephrons, which reduces the kidney’s ability to filter blood. H. Decreased blood urea nitrogen (BUN) is incorrect. BUN rises during the oliguric phase due to the inability to excrete nitrogenous waste, so low BUN would be unexpected. I. Increased potassium is correct. Hyperkalemia develops because the kidneys cannot excrete potassium, which is potentially life-threatening. This finding requires frequent monitoring and interventions such as dietary restriction, medications to shift potassium into cells, or dialysis in severe cases.