A client has a new prescription for diclofenac, a nonsteroidal antiinflammatory drug (NSAID). Which information in the client's history is of greatest concern to the nurse in monitoring the client's response to this medication?

A. Worsening headache:
Vasopressin is used to manage diabetes insipidus by reducing excessive urine output and increasing water reabsorption. A worsening headache could indicate an adverse reaction or side effect such as water intoxication or an increase in intracranial pressure, which requires immediate attention from the healthcare provider.

B. Low urine specific gravity:
Vasopressin should increase urine specific gravity by concentrating the urine. A low urine specific gravity would indicate that the medication is not effectively concentrating the urine, but it is not an immediate or severe side effect needing urgent reporting.

C. Polyuria:
Polyuria (excessive urine output) is a characteristic of diabetes insipidus, and vasopressin is intended to reduce this symptom. If polyuria persists despite treatment, it suggests that the medication is not working as intended but does not indicate a severe side effect.

D. Polydipsia:
Polydipsia (excessive thirst) can occur in diabetes insipidus and may continue despite treatment with vasopressin. While it indicates ongoing symptoms, it is not a severe side effect of the medication that would require urgent reporting to the healthcare provider.

A) Diarrhea: Diarrhea is a common side effect of many medications, including those used for nausea and vomiting. While it can be uncomfortable and may require management, it is generally less severe compared to neurological symptoms. Persistent diarrhea should be monitored and managed, but it does not typically indicate a serious underlying issue with metoclopramide.

B) Unusual irritability: Irritability can occur as a side effect of many medications and might be a sign of a mild central nervous system effect or a response to the stress of illness. While it is important to assess and address any changes in mood, unusual irritability is generally less urgent compared to neurological symptoms that could suggest more serious adverse effects.

C) Involuntary movements: Involuntary movements, such as tremors or muscle spasms, are significant concerns when a patient is on metoclopramide. These symptoms can indicate extrapyramidal side effects, which include tardive dyskinesia or other severe movement disorders. These conditions can be serious and potentially irreversible if not addressed promptly, making it crucial to report such symptoms immediately to the healthcare provider for further evaluation and intervention.

D) Nausea: Nausea is the primary symptom that metoclopramide is intended to treat, so its presence is expected and does not usually signal an adverse reaction to the medication. If nausea persists despite treatment, it might suggest the need for dose adjustment or an alternative treatment, but it is not an urgent adverse effect that requires immediate reporting compared to neurological symptoms.