Conclusions: We report details on possible PTU-associated birth defects.

The method was successfully applied for the determination of PTU and MTZ in real samples.

SCr returned to baseline within 2 weeks of methimazole discontinuation, and the patient was subsequently managed on PTU.

After subtotal thyroidectomy with discontinuance of PTU the patient remained asymptomatic for the last two and half years.

These findings indicate that the patient developed autoimmune neutropenia by producing opsonic antineutrophil antibodies in association with the PTU therapy.