Periodic Granulocyte Count Measuring Is Useful for Detecting Asymptomatic Agranulocytosis in Antithyroid Drug-Treated Patients with Graves' Disease

Objective: Finding agranulocytosis (AG) at an early stage is important to improve outcome, but periodic granulocyte count monitoring is not generally recommended for patients with Graves' disease, because AG develops suddenly. Method: At the Kuma Hospital, Graves' patients under antithyroid drug (ATD) treatment in an outpatient clinic have a granulocyte count examination during each visit, and if it is <1,000/μl, a warning is immediately sent to the patient's physician. We evaluated the usefulness of this system. Results: We investigated 25 AG and 33 granulocytopenia (GP) cases over a recent 5-year period, excluding patients who developed AG or GP at another hospital and were referred to us for treatment. Among the 25 AG patients, 16 patients (64%; 9 asymptomatic and 7 very mild symptomatic cases) were discovered by the periodic granulocyte count examination at an outpatient clinic. The remaining 9 patients visited the Kuma Hospital or other hospitals because of infection symptoms. Most of the AG patients were given granulocyte colony-stimulating factor injections immediately and were admitted if a prompt increase in granulocytes could not be obtained. The final treatments for Graves' disease were 131I-radioisotope therapy (19 patients), thyroidectomy (2 patients), inorganic iodine (1 patient), or another ATD (1 patient). Among the 33 GP patients, 31 (94%), including 20 asymptomatic cases, were discovered during periodic granulocyte count monitoring. Most of them stopped ATD, and other treatments for Graves' disease were selected. Conclusion: Periodic monitoring of granulocyte counts is useful for identifying AG and GP patients with no or minimum infection symptoms.