Clostridium difficile colitis in the setting of subacute thyroiditis: the chicken or the egg

Subacutethyroiditis is a self-limited inflammatory condition commonly of viral aetiology, that manifests through phases of thyroid hormone changes over a 6-8 month period. A 24-year-old active duty military man, undergoing treatment for recurrent Clostridiumdifficile infection, presented for clinical evaluation and was found to have a thyroid stimulating hormone level of 0.003 mg/dL. Further labs revealed a normal T4, elevated T3 at 5.0 pg/mL and elevated C reactive protein at 3.69 mg/L. The patient was followed with monthly labs and the abnormal thyroid stimulating hormone and triiodothyronine levels resolved after the completion of his C. difficile treatment. While subacute thyroiditis has historically been due to viral causes, rarely do we see this condition associated with an intestinal bacterial source.