Monitoring Antithyroid Therapy

In 1990 Tajiri et al¹ described a subgroup of Japanese patients receiving antithyroid therapy (ATD) for thyrotoxicosis in whom asymptomatic severe granulocytopenia progressed to symptomatic agranulocytosis. On the basis of this observation, they questioned the concept that ATD-induced agranulocytosis is of explosive onset. Although they did not suggest a specific frequency or duration of testing, they advised a routine white blood cell (WBC) count monitoring of patients receiving ATD. They now report data that they interpret as showing the effectiveness of granulocyte colonystimulating factor in ATD-induced mild to moderate granulocytopenia. They cite this observation as further evidence of the importance of a WBC count monitoring of ATD.²

That Tajiri et al were able to accumulate three patients with agranulocytosis in 1 year is somewhat surprising. It is even more remarkable that in the same period they found 13 patients with mild to moderate granulocytopenia. We (R.S. and S.G.)