Problem: A patient presents with a serum magnesium level of 2.8 mg/dL. Conclude what additional information the nurse practitioner should obtain from the medical history or physical exam. Tetany (e.g., positive Trousseau's or Chvostek's sign or spontaneous carpopedal spasm and hyperreflexia) Critically ill patients who are receiving total parenteral nutrition History of acute or chronic renal failure Generalized weakness