The nurse has just completed an infusion of a 1000 ml bolus of 0.9% normal saline in a patient with severe sepsis. One hour later, which laboratory result requires immediate nursing action?

Rationale: A. Potassium 3.8 mEq/L is incorrect because this value is within the normal reference range of 3.5–5.0 mEq/L. While potassium should continue to be monitored—especially in critically ill patients due to risks of hypokalemia or hyperkalemia from fluid shifts or medications—this reading does not indicate an immediate complication or urgent need for intervention. B. Sodium 140 mEq/L is incorrect because it falls within the normal serum sodium range of 135–145 mEq/L. This value suggests that the recent fluid administration has not caused significant electrolyte imbalance, and no immediate action is required. C. Creatinine 1.0 mg/dl is incorrect because this is within the normal range (approximately 0.6–1.3 mg/dL) and does not indicate acute kidney injury at this time. While renal function must be monitored in septic patients due to the risk of acute kidney injury from hypoperfusion, this value alone is not alarming. D. Lactate 6 mmol/L is correct because an elevated lactate level in a patient with severe sepsis is a critical indicator of tissue hypoperfusion, anaerobic metabolism, and possibly septic shock, even after aggressive fluid resuscitation. Normal lactate levels are 4 mmol/L are associated with high mortality risk.