A nurse is caring for a client who had total thyroidectomy and a serum calcium level of 7.6 mg/dL. Which of the following findings should the nurse expect?

Choice A rationale Hypocalcemia, defined as a serum calcium level below 9.0 mg/dL (in this case 7.6 mg/dL), typically causes a prolongation of the QT interval on an electrocardiogram, not a shortening. A prolonged QT interval occurs because the phase 2 of the cardiac action potential is extended due to the effect of low calcium on the myocardial cells. Shortened QT intervals are more commonly seen in hypercalcemia, where serum calcium levels exceed 10.5 mg/dL. Choice B rationale Constipation is a clinical manifestation of hypercalcemia, which slows gastrointestinal motility and smooth muscle contraction. In contrast, hypocalcemia often leads to increased neuromuscular irritability, which can result in hyperactive bowel sounds or diarrhea rather than constipation. With a calcium level of 7.6 mg/dL, the nurse should expect signs of increased excitability in the nervous system and musculature rather than the depressive effects on the gut seen with high calcium. Choice C rationale Hypocalcemia is characterized by neuromuscular irritability and hyperreflexia, meaning the nurse would expect hyperactive deep tendon reflexes. When serum calcium levels drop below 9.0 mg/dL, the threshold for nerve stimulation is lowered, causing muscles to twitch or spasm more easily. Hypoactive reflexes are associated with hypercalcemia or hypermagnesemia, where the excess cations have a sedative effect on the neuromuscular junction, reducing the intensity of the reflex response. Choice D rationale Tingling of the extremities, or paresthesia, is a hallmark sign of hypocalcemia. A serum calcium level of 7.6 mg/dL increases peripheral nerve excitability, leading to sensations of numbness and tingling, especially in the fingers, toes, and circumoral area. This occurs because low extracellular calcium levels increase sodium permeability in nerve membranes, causing spontaneous depolarization. This is a critical finding that often precedes more severe symptoms like tetany, Chvostek's sign, or Trousseau's sign.