Endocrine Abstracts

A 22-year old female diagnosed with thyrotoxicosis with raised free thryroxine (16.8 pmol/l) and suppressed thyroid-stimulating-hormone (TSH<0.03 mIU/l). She was started on Carbimazole 20 mg during end of August 2011. A fortnight later she presented with nausea, vomiting, fever and rigors. Her renal functions were deranged with a creatinine of 704 μmol/l, which worsened over the next 48 h. She subsequently needed renal replacement therapy with haemodialysis. She was cytpolasmic anti-neutrophil cytpolasmic antibody (c-ANCA) positive with raised proteinase-3 (PR3) titers (28AU/ml) (see Table). She was negative for anti-thyroid stimulating hormone (TSH) receptor antibodies, anti-glomerular basement membrane (GBM) antibody and for anti-nuclear antibodies with normal complement levels.

It was proposed, perhaps this could be drug-(carbimazole)-induced renal vasculitis with positive c-ANCA; for which carbimazole was stopped and a renal biopsy revealed concentric necrotizing-glomerulonephritis consistent with c-ANCA-positive-vasculitis. She was further treated with high dose prednisolone and cyclophosphamide following which her renal functions improved and she was weaned-off haemodialysis; subsequently her thyroid function tests also normalized without any further anti-thyroid therapy.

Conclusion: Our case report re-iterates that anti-neutrophil-cytoplasmic-antibody-(ANCA)-associated-vasculitis is a potentially life-threatening adverse effect of anti-thyroid drugs like carbimazole. Altered immune environment associated with autoimmune thyroid disease is not sufficient to develop ANCA but treatment with thionamides (which accumulate in neutrophils) is important in promoting ANCA development. There is only limited literature available describing carbimazole-induced-ANCA-positive renal vasculitis; and as in other case reports, renal function improved after stopping carbimazole and immunosuppressive therapy.

Figure 1 Renal biopsy (with silver stain) with glomerulus showing fibrinoid necrosis of the glomerular tuft surrounded by a cellular crescent.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.