Endocrine Abstracts

Introduction: Vasculitis is a rare complication of anti-thyroid medications and is more common with propylthiouracil than carbimazole. Patients often have multisystem involvement although renal and dermatological manifestations are common. Although most cases resolve following withdrawal of the offending agent, not all do and rare instances of death have been reported in the literature. Immunosuppressive therapy can be used to improve organ function and prevent progression.

Case report: A 68-year-old man presented with fever, heat intolerance and weight loss. He was clinically and biochemically thyrotoxic with T₄ 37.3 pmol/l and TSH <0.01 mU/l. There was no evidence of intercurrent infection. He was initiated on Carbimazole 40 mg once daily for presumed Graves’ disease. Three weeks later he complained of diffuse erythematous skin rash affecting his trunk and limbs with typical features of vasculitic rash. Carbimazole was discontinued at the time. However, his clinical condition deteriorated with anorexia, weakness and weight loss. Investigation revealed worsening thyrotoxicosis and new onset renal failure. Urea 21 mmol/l, serum creatinine 194 ummol/l, ESR 73 ml/min, significantly raised myeloperoxidase ANCA antibody (36 IU/ml), strongly positive rheumatoid factor (227 IU/ml) and positive anti-nuclear antibody. Skin biopsy and renal biopsy were inconclusive and proteinase-3 ANCA antibody was negative. However, in view of the typical skin lesion, renal failure, raised ESR and high myeloperoxidase ANCA titre, diagnosis of carbimazole-induced vasculitis was made and he was commenced on intravenous methylprednisolone 500 mg for 3 days followed by oral corticosteroids. Radioiodine therapy (800 MBq) was administered along with beta blockers under close supervision.

He is now hypothyroid and is on thyroxine replacement. Despite high dose prednisolone he remains in renal failure, although his renal function has stabilised, skin lesions have subsided and repeat ANCA titre is negative.

In summary, we have presented a patient with carbimazole-induced vasculitis with partial response to withdrawal of offending agent and use of corticosteroids.