Usefulness of granulocyte count measurement four hours after injection of granulocyte colony-stimulating factor for detecting recovery from antithyroid drug-induced granulocytopenia.

This prospective study was designed to investigate the usefulness of granulocyte count measurements 4 hours after injection of granulocyte colony-stimulating factor (G-CSF) for detecting recovery from antithyroid drug (ATD)-induced granulocytopenia or agranulocytosis. Granulocyte and white blood cell counts were measured 4 hours and 24 hours after patients with ATD-induced granulocytopenia had been given an injection of 75 micrograms of G-CSF (1.1 to 1.9 micrograms/kg; 1.5 +/- 0.2 micrograms/kg [mean +/- standard deviation]). Thirty-seven patients were studied and divided into three groups based on their initial granulocytopenic granulocyte count: 28 with mild (granulocyte count 0.501 to 1.0 x 10(9)/L), 6 with moderate (granulocyte count 0.101 to 0.5 x 10(9)/L), and 3 with severe (granulocyte count less than 0.1 x 10(9)/L) ATD-induced granulocytopenia. Twenty-five of the 28 patients with mild granulocytopenia and 4 of the 6 patients with moderate granulocytopenia were found to have recovered from the granulocytopenia both 4 hours and 24 hours after injection, and their granulocyte counts remained normal thereafter. However, the other 3 patients with mild granulocytopenia, 2 patients with moderate granulocytopenia, and all 3 patients with severe granulocytopenia had not recovered by either 4 or 24 hours after the G-CSF injection. Despite daily G-CSF injections, the granulocyte continued to decrease in most cases. It took 2 to 11 days for these counts to recover from granulocytopenia. These results indicate that granulocyte count measurement 4 hours after injection of G-CSF is useful for detecting recovery from ATD-induced granulocytopenia or agranulocytosis and for predicting disease severity. Accordingly, its measurement enables physicians to make an appropriate decision about whether a patient with ATD-induced granulocytopenia should be treated in the hospital or in the outpatient clinic.