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Two Cases of Methimazole-Induced Agranulocytosis With Their Risk Factors
Aye Khine1, Kiranjit Dhillon1, Linda Jo1
1Department of Internal Medicine, University of California San Francisco-Fresno, Fresno, California.
Background:
Antithyroid drugs, such as methimazole (MMI), are standard therapies for the medical management of thyrotoxicosis. Agranulocytosis is a rare but lethal adverse effect of antithyroid medications. We have reported 2 cases of MMI-induced agranulocytosis with similar risk factors that likely predisposed them to this adverse reaction.
Case Report:
Case 1 involved a 71-year-old woman, with a history of Graves disease, who presented with an altered mental status. She was recently discharged on 40 mg of MMI twice daily, and she continued this dose for 2 months. She was readmitted and found to have neutropenic fever in the setting of MMI-induced agranulocytosis. MMI was discontinued, and she was started on filgrastim. Her cell counts gradually improved, and she was subsequently discharged.Case 2 involved a 68-year-old woman, with a history of Graves disease, who presented with severe back pain, nausea, and vomiting. She was recently discharged on 10 mg of MMI twice daily, which was increased to 10 mg 3 times a day. She was readmitted to the hospital because of a septic shock in the setting of pneumonia, colitis, bacteremia, and MMI-induced agranulocytosis. A bone marrow biopsy showed a polyclonal infiltrate with up to 85% plasma cells. Despite treatment with antibiotics, filgrastim, and continuous renal replacement therapy, she ultimately passed away.
Discussion:
Although these cases had differing outcomes, they shared similar features and risk factors, including older age, female sex, and relatively higher doses of MMI.
Conclusion:
Close follow up and awareness of risk factors, such as age, female sex, and higher doses of MMI, may decrease the risk of MMI-induced agranulocytosis and fatal outcomes.
Insights
Methimazole (MMI) can cause agranulocytosis, a dangerous drop in white blood cells. Older women on higher MMI doses face increased risk. Awareness and monitoring are key to preventing severe outcomes.
Area of Science:
- Endocrinology
- Pharmacology
- Hematology
Background:
- Antithyroid drugs like methimazole (MMI) are standard for thyrotoxicosis treatment.
- Agranulocytosis is a rare but potentially fatal adverse effect of antithyroid medications.
- This report details two cases of MMI-induced agranulocytosis with shared risk factors.
Observation:
- Case 1: A 71-year-old woman with Graves disease developed neutropenic fever due to MMI. Treatment with filgrastim led to recovery.
- Case 2: A 68-year-old woman with Graves disease experienced septic shock from MMI-induced agranulocytosis, complicated by pneumonia and bacteremia. Despite aggressive treatment, she died.
Findings:
- Both patients were older females with Graves disease.
- Higher doses of MMI were administered to both patients.
- Similar risk factors, including advanced age, female sex, and elevated MMI dosage, predisposed these patients to agranulocytosis.
Implications:
- Awareness of risk factors such as age, sex, and MMI dose is crucial for early detection.
- Close patient monitoring can mitigate the risk of severe MMI-induced agranulocytosis.
- Prompt management, including MMI discontinuation and supportive care, is essential for improving patient outcomes.
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