A nurse is administering desmopressin to a client who has diabetes insipidus. The nurse should monitor the client for which of the following adverse effects?

Desmopressin is a synthetic analogue of antidiuretic hormone (ADH) that increases water reabsorption in the collecting ducts of the kidney. It is the primary treatment for central diabetes insipidus, effectively concentrating urine and reducing excessive thirst and polyuria. Monitoring for water intoxication is the priority nursing intervention. Rationale: A. Bradycardia is not a direct adverse effect associated with desmopressin administration. While significant fluid overload could theoretically stress the cardiovascular system, a slow heart rate is not the specific parameter used to monitor for desmopressin toxicity. The nurse should focus instead on signs of volume expansion and electrolyte shifts, particularly those affecting the neurological system and sodium balance. B. Fluid retention is a primary adverse effect of desmopressin because the drug effectively stops the kidneys from excreting water. If the client continues to drink large amounts of fluid while taking the drug, they are at risk for water intoxication and dilutional hyponatremia. The nurse must monitor for headache, confusion, and edema, which indicate that the body is retaining too much free water. C. Blurred vision is not a common or direct side effect of desmopressin therapy. Visual changes are more often linked to medications that affect the autonomic nervous system or those with anticholinergic properties. However, if blurred vision occurs in the context of a severe headache while on desmopressin, it could be a sign of increased intracranial pressure from severe water intoxication. D. Hypernatremia is the condition desmopressin is meant to treat in a patient with diabetes insipidus, not an adverse effect of the drug. Desmopressin causes water retention, which dilutes the blood and lowers the sodium concentration. Therefore, the nurse should monitor for the opposite effect, hyponatremia, which occurs if the medication works too effectively or if fluid intake is excessive.