OBJECTIVE: A retrospective cross-sectional analysis with an ethnicity-matched control cohort examining the relationship between free thyroxine (FT4), thyroid-stimulating hormone receptor antibody (TRAb) and absolute neutrophil count (ANC) in newly diagnosed hyperthyroidism, and assessing the influence of ethnicity on ANC. METHODS: Adults with newly diagnosed hyperthyroidism between August 2020 to July 2025 and concurrently available FT4, TRAb and ANC were included. Graves' disease (GD) was defined by Roche Elecsys TRAb ≥ 1.75 IU/L. An ANCOVA tested main effects of TRAb and FT4 on ANC and their interaction. ANC was compared between GD and non-GD hyperthyroidism and with euthyroid controls, stratified by Asian, Black and White ethnicities. RESULTS: , p = 0.002) upon achieving euthyroidism. CONCLUSIONS: Graves' hyperthyroidism is associated with ANC decrease that is greatest when substantially high TRAb and FT4 coexist. ANC is further influenced by ethnicity. Mild neutropenia, particularly in ethnicities predisposed to benign ethnic neutropenia, should not delay antithyroid treatment.
More et al. (Wed,) studied this question.