Hello and welcome – hopefully, others here will chime in with their experiences. The American Thyroid Association recommends “reconsidering” whether to start ATDs if the baseline absolute neutrophil count is <1000mm3. Normal ranges can vary from lab to lab, but my understanding is that this is *below* the normal range. The ATA also notes that low WBC is a common occurrence with Graves'.
Potential signs & symptoms of a serious side effect with antithyroid meds include sore throat with fever and mouth sores. Check with your doc in advance on what to do if you should experience these issues. Most will ask you to call ASAP and come in for a blood test; they might also have you stop the meds until the results are back.