A nurse is assisting with the care of a client who has a serum calcium level of 7.2 mg/dL (9 to 10.5 mg/dL). Which of the following manifestations should the nurse anticipate?

The client scenario features a patient exhibiting a deficient serum calcium concentration below normal limits. To anticipate manifestations, principles of neuromuscular excitability, sodium channel gating mechanisms, and peripheral nerve depolarization thresholds must be accurately applied. Choice A rationale Cullen sign represents ecchymosis around the periumbilical region, indicating retroperitoneal hemorrhage typically associated with acute pancreatitis. While pancreatitis can cause hypocalcemia due to fat saponification, the sign itself is not caused by low calcium. Choice B rationale Extracellular calcium ions stabilize excitable membranes. When calcium drops below the normal range of 9 to 10.5 mg/dL, voltage-gated sodium channels open more easily, increasing neuromuscular excitability and causing hyperactive deep tendon reflexes, tremors, and tetany. Choice C rationale Hypocalcemia typically causes hypotension, not hypertension, because calcium ions are essential for myocardial contractility and vascular smooth muscle tone. Deficient calcium levels impair cardiac contraction strength and reduce peripheral vascular resistance, lowering systemic blood pressure. Choice D rationale Increased neuromuscular excitability from low calcium levels stimulates the smooth muscle of the gastrointestinal tract. This process accelerates peristaltic contractions, which manifests clinically as hyperactive bowel sounds and abdominal cramping rather than hypoactive sounds.