A nurse is analyzing the diagnostic test results of an older adult female client who is preoperative for a knee arthroplasty. The nurse should notify the surgeon of which of the following results?

Choice A reason: A hematocrit of 40% is within the normal range for adult females (generally 36–46%). This value indicates adequate red blood cell mass and oxygen-carrying capacity, so it does not require immediate notification to the surgeon. Choice B reason: A potassium level of 3.8 mEq/L is within the normal range (3.5–5.0 mEq/L). Potassium is critical for cardiac and neuromuscular function, but this value does not pose a risk for surgery and does not require urgent reporting. Choice C reason: A creatinine level of 0.9 mg/dL is normal (0.6–1.3 mg/dL). This indicates adequate renal function, which is important for medication metabolism and fluid balance during surgery. Since the value is normal, it does not require notification. Choice D reason: A WBC count of 20,000/mm³ is significantly elevated, indicating possible infection or severe inflammatory response. Surgery should not proceed in the presence of untreated infection because it increases the risk of postoperative complications such as sepsis, poor wound healing, and prosthetic joint infection. This abnormal result requires immediate notification to the surgeon.