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. Sodium level of 130 mEq/L is slightly below the lower limit of the reference range but might not have as immediate an impact on safety as a critically low hemoglobin level. B. Hemoglobin of 8.9 grams/dL is significantly below the normal range and indicates a substantial drop in red blood cells, which can lead to impaired oxygen transport and potentially severe postoperative complications like inadequate tissue perfusion and oxygenation. C. Potassium level of 3.4 mEq/L is slightly below the lower limit of the reference range but might not pose an immediate threat compared to a critically low hemoglobin level. D. Blood urea nitrogen (BUN) of 20 mg/dL is at the upper limit of the reference range but might not have an immediate implication for client safety compared to a critically low hemoglobin level.