The practical nurse (PN) reviews the laboratory results of an elderly female client who is one day postoperative for a right total hip replacement (THR). Which serum value result has the greatest implication for client safety? Reference ranges Hemoglobin (Hgb) [12 to 16 g/dL (120 to 160 g/L)] Potassium (K+) [3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L)] Sodium [136 to 145 mEq/L (136 to 145 mmol/L)] Blood Urea Nitrogen (BUN) [10 to 20 mg/dL (3.6 to 7.1 mmol/L)]

A. Hemoglobin 8.9 grams/dL: This value is significantly below the normal range and indicates anemia, likely from perioperative blood loss. Low hemoglobin can compromise oxygen delivery to tissues, increase risk for hypoxia, delay healing, and may require urgent intervention such as transfusion or close monitoring. B. Sodium 130 mEq/L: Mild hyponatremia requires monitoring and assessment for symptoms like confusion or weakness, but it is generally less immediately life-threatening than significant anemia in a postoperative client. C. Potassium 3.4 mEq/L: Mild hypokalemia may predispose the client to arrhythmias, but it is not as immediately critical as severe anemia affecting oxygen-carrying capacity. Monitoring and potassium replacement can be implemented. D. Blood urea nitrogen 20 mg/dL: This value is at the upper limit of normal and does not indicate acute renal compromise. While it warrants monitoring, it does not pose an immediate threat to client safety in the postoperative setting.