A nurse is caring for a client with a history of hyperthyroidism who presents with depression, weight gain, and cold intolerance. Which medication most likely caused the signs and symptoms?

Rationale: A. Levothyroxine: Levothyroxine is a synthetic thyroid hormone used to treat hypothyroidism. It increases metabolic activity, energy levels, and thermogenesis. Administration of levothyroxine would typically cause symptoms of hyperthyroidism if overdosed, such as weight loss, heat intolerance, and anxiety, rather than depression, weight gain, and cold intolerance. B. Metformin: Metformin is an oral antihyperglycemic used in type 2 diabetes mellitus. Its common side effects include gastrointestinal upset and, rarely, lactic acidosis. It does not affect thyroid hormone levels and is unlikely to cause hypothyroid-like symptoms such as depression, cold intolerance, or weight gain. C. Propylthiouracil: Propylthiouracil (PTU) is an antithyroid medication used to treat hyperthyroidism by inhibiting thyroid hormone synthesis. Excessive dosing or prolonged therapy can lead to hypothyroidism, which manifests as depression, weight gain, bradycardia, cold intolerance, and fatigue, matching the client’s current presentation. D. Ipratropium: Ipratropium is an anticholinergic bronchodilator used in respiratory conditions such as COPD and asthma. It primarily affects muscarinic receptors in the lungs and has minimal systemic metabolic effects. It is not associated with thyroid hormone suppression or hypothyroid-like symptoms.