Situation: A 34-year-old woman with Graves disease is admitted for total thyroidectomy because a large goiter makes swallowing difficult. She has taken methimazole for 3 months, and potassium iodide solution was added 9 days ago. She has no known drug allergies. At a clinic visit 1 month before admission, she reports a sore throat and chills. Her temperature is 38.4 °C (101.1 °F), and her methimazole dose is due now. Which action should the nurse take?

Fever with a sore throat in a client taking a thionamide such as methimazole may signal agranulocytosis. The dose is held and the provider is notified at once so that a complete blood count with differential can be checked before any further dose.

Core clinical concern

A 34-year-old woman with Graves disease is taking methimazole, a thionamide antithyroid drug. One month before surgery she develops fever (38.4 °C) and a sore throat. In a patient on a thionamide, this combination is a red-flag presentation for agranulocytosis, a severe and potentially fatal drop in neutrophils.

Fever plus sore throat in a patient taking methimazole must be treated as possible agranulocytosis until a complete blood count with differential proves otherwise. The correct nursing action is to hold the dose and notify the provider immediately.

Why this presentation is dangerous

Methimazole suppresses thyroid hormone synthesis by inhibiting thyroid peroxidase. However, it can also cause idiosyncratic bone marrow suppression, most critically agranulocytosis, defined as an absolute neutrophil count below 500 cells/mm³. Neutrophils are the first line of defense against bacterial infection, especially in the oropharynx.

When neutrophils are severely depleted, the earliest clinical signs are often:

- Sore throat due to oropharyngeal mucosal breakdown and bacterial invasion
- Fever from systemic infection
- Chills, malaise, and sometimes oral ulcerations

The sore throat is not a simple viral pharyngitis; it is a warning sign that the patient may have almost no circulating neutrophils to contain oral flora. If another dose of methimazole is given, the marrow suppression may worsen, and the patient may progress rapidly to septic shock.

Why the other options are unsafe

Option	Action	Why it is incorrect
2	Give the dose and send a throat swab culture	Giving methimazole before ruling out agranulocytosis risks further neutrophil destruction. A throat culture takes time and does not address the immediate danger.
3	Give the dose and offer warm saline gargles	Symptomatic gargles do nothing for agranulocytosis, and continuing the drug is contraindicated until a CBC with differential is checked.
4	Give paracetamol and recheck later	Antipyretics may mask fever, delaying recognition of a life-threatening infection. Rechecking later wastes critical time.

Nursing priority and sequence

The immediate nursing actions are:

1. Hold the methimazole dose — do not administer any further thionamide until the provider evaluates the patient.
2. Notify the provider at once — report the fever, sore throat, and current medication history.
3. Anticipate a complete blood count with differential to confirm or exclude agranulocytosis.
4. Institute infection precautions if neutropenia is confirmed, and monitor for signs of sepsis such as hypotension, tachycardia, or altered mental status.

Clinical timing and risk window

Agranulocytosis from thionamides most often occurs within the first 3 months of treatment, which matches this patient’s 3-month methimazole course. The addition of potassium iodide 9 days before admission is used preoperatively to reduce thyroid vascularity, but it does not protect against methimazole-induced marrow suppression.

The timing of symptom onset within the first few months of thionamide therapy is a classic feature of drug-induced agranulocytosis. Patients are typically instructed to report any fever, sore throat, or mouth ulcers immediately and to stop the drug until a blood count is checked.

Exam-focused comparison

Feature	Agranulocytosis from methimazole	Simple viral pharyngitis
Fever and sore throat	Present	Present
Drug history	Thionamide within past 3 months	No relevant drug
Risk	Rapid progression to sepsis	Self-limiting
Required action	Hold drug, notify provider, CBC with differential	Symptomatic care

Key takeaway

Any fever with sore throat in a patient on methimazole or propylthiouracil is agranulocytosis until proven otherwise. The drug is held, the provider is notified immediately, and a CBC with differential is obtained before any further dose is considered.