A 22-year-old woman comes to the emergency department due to fever and a sore throat. Her medical history is significant for Graves disease, for which she recently began taking an antithyroid medication. The patient has no other medical conditions and does not use tobacco, alcohol, or illicit drugs. She works as a teacher at an elementary school. Temperature is 38.9 C (102 F), blood pressure is 110/70 mm Hg, and pulse is 90/min. Physical examination shows an erythematous pharynx and a normal-sized thyroid. There is no tremor of the outstretched hands. Which of the following is the most likely cause of this patient's current condition?

Question

A 22-year-old woman comes to the emergency department due to fever and a sore throat.  Her medical history is significant for Graves disease, for which she recently began taking an antithyroid medication.  The patient has no other medical conditions and does not use tobacco, alcohol, or illicit drugs.  She works as a teacher at an elementary school.  Temperature is 38.9 C (102 F), blood pressure is 110/70 mm Hg, and pulse is 90/min.  Physical examination shows an erythematous pharynx and a normal-sized thyroid.  There is no tremor of the outstretched hands.  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

11ec160b_3bb9_8d8c_9249_51b6135bd6d5_MD0001_00 Antithyroid drugs (eg, propylthiouracil [PTU], methimazole) inhibit thyroid peroxidase and are used to decrease thyroid hormone production in patients with hyperthyroidism (eg, Graves disease). However, antithyroid drugs are associated with an increased risk for agranulocytosis, typically in the first few months of therapy. This is an idiosyncratic and potentially life-threatening side effect of therapy and is likely due to both immune-mediated effects (via generation of antineutrophil cytoplasmic antibodies) and direct bone marrow toxicity (via generation of reactive oxygen species). Patients with drug-induced agranulocytosis (absolute neutrophil count <500/mm³) are at risk for severe infection; oropharyngeal infection (eg, fever, sore throat, oral ulcerations) is the most common initial manifestation, and sepsis can develop quickly thereafter. Complete blood count with differential will show neutropenia without anemia or thrombocytopenia; bone marrow biopsy will reveal a reduction in granulocyte precursors. Agranulocytosis is reversible on discontinuation of the drug. (Choice A) Patients with autoimmune thyroid disease are at risk for other autoimmune endocrinopathies, including adrenal insufficiency. However, acute adrenal crisis typically presents with refractory hypotension, vomiting, abdominal pain, and weakness. (Choices C and D) Excessive suppression of thyroid function by antithyroid drugs leads to a hypothyroid state characterized by fatigue, weight gain, cold intolerance, and hair and skin changes. Undertreatment would result in a residual hyperthyroid state, with anxiety, tachycardia, tremor, and heat intolerance. Neither hyper- nor hypothyroidism typically present with a febrile pharyngeal infection. (Choice E) A number of viruses can cause neutropenia, including HIV, viral hepatitis (A, B, C), and the herpesvirus group (varicella zoster virus, Epstein-Barr virus, cytomegalovirus, human herpesvirus-6). However, the recent initiation of an antithyroid drug makes drug-induced agranulocytosis more likely. Educational objective: Agranulocytosis is a serious complication of antithyroid drugs (eg, methimazole, propylthiouracil) that results from drug-induced granulocyte destruction and consequent neutropenia. Initial manifestations often include fever, sore throat, and oral ulcerations. If drug-induced agranulocytosis is suspected, the drug should be discontinued immediately and a complete blood count with differential should be obtained to help confirm the diagnosis. __________ References: Antithyroid drug-induced agranulocytosis: state of the art on diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/28105610)

A 22-Year-Old Woman Comes to the Emergency Department Due to Fever