This is a-46 years-old female was admitted in Qurayyat general hospital with Cardiomyopathy and Hyperthyroidism, was put on Carbimazole 60 mg orally daily.

Background: Hyperthyroidism four weeks back on Carbimazole 60 mg orally daily.

Presentation: This patient presented with few days of palpitation and general fatigue, found have Cardiomyopathy, with severe neutropenia (Agranulocytosis), managed by cardiac team for Cardiomyopathy, with internal medicine team for her neutropenia. Carbimazole was stopped immediately. Started on Filgrastim a Granulocyte colony-stimulating factor (G-CSF) 300 mcg SC daily, with neutropenic antibiotic coverage and application of isolation precautions. But there was no response to Filgrastim initially. However, after 7 days of administering Filgrastim, WBC with neutrophil started to recover and increase in number, returned to normal range on day 9 of treatment, so Filgrastim was stopped. However, WBC and Neutrophil showed rebound increase in the next three days until reached 50.600/ cmm, and then returned again to normal range on day 13.

Her cardiac condition stabilized on cardiac medication.

Conclusion: Carbimazole is used to treat hyperthyroidism; however, Agranulocytosis is a rare but potentially life-threatening side effect occurs during the first few months of treatment. If patients develop symptoms such as fever or a sore throat, blood tests should be performed immediately, and Carbimazole should be discontinued if Agranulocytosis is suspected.