A RARE SIDE EFFECT OF CARBIMAZOLE

Abstract

INTRODUCTION
Carbimazole therapy is associated with a variety of adverse reactions, among the rarest being interstitial pneumonia.

CASE
An 18-year-old primigravid, non-smoker at POA of 28 weeks 5 days presented with fever and progressively worsening dyspnea occurring within a week. She had Graves’ disease diagnosed just prior to pregnancy and was on carbimazole 30mg od since then. Rapid deterioration of her respiratory state required mechanical ventilation. Pulmonary auscultation revealed coarse crepitation at right lower zone. She was clinically euthyroid and had a diffuse goiter with absence of thyroid eye signs. Chest x-ray showed diffuse interstitial peripheral opacities. Computed tomography of the thorax revealed patchy ground glass opacities located at the subpleural regions, peripherally and the peribronchovascular areas in both upper, middle and lower lobes suggestive of cryptogenic organizing pneumonia. Culture of both blood and tracheal secretions were negative. Vasculitis as a cause of organizing penumonia has been sought however due to lack of other peripheral features and negative anti-neutrophil antibodies (ANA) and anti-neutrophil cytoplasmic antibodies (ANCA) render it less likely. A diagnosis of carbimazole-induced organizing pneumonia was made which led to carbimazole discontinuation, and introduction of oral prednisolone of 1mg/kg/day. The patient rapidly improved with eventual resolution of the lung disease.

CONCLUSION
Carbimazole given for hyperthyroidism can rarely cause severe pneumonitis requiring ventilation. Carbimazole should be withdrawn in the presence of respiratory symptoms and documented interstitial pneumonia.