Endocrine Abstracts

We present a case of 76-year-old male who attended acute medical unit with 3 week history of confusion, slurred speech and reduced mobility. One month prior to his admission he was diagnosed with severe hypothyroidism with TSH of 100 mU/l and T₄ of 1.9 pmol/l and significantly positive anti-peroxidase antibodies (561 IU/ml) and was started on 100 μg of levothyroxine by his GP. During his admission his confusion persisted despite antibiotics for presumed chest infection. He had associated hyponatraemia and postural blood pressure drop of 40 mmHg. His Short Synacthen test was abnormal with baseline and stimulated cortisol of 55 and 130 nmol/l respectively. Diagnosis of Addison’s disease was made and this was most likely exacerbated by infection and recently commenced levothyroxine. He was also found to have primary testicular failure (testosterone, 4.6 nmol/l; FSH, 63.6 IU/l; LH, 32.3 IU/l) with anaemia. Lumbar puncture was performed and showed raised CSF protein of 1917 mg/l. Bacterial and viral CNS infection was excluded. EEG was in keeping with mild encephalopathy and MRI showed periventricular white matter changes associated with inflammation. Diagnosis of Hashimoto encephalitis was made after exclusion of other causes of encephalitis. Patient was started on prednisolone 40 mg od and his confusion fully resolved after 2 months of therapy. Dose was down-titrated to 5 mg od over 12 months.

Discussion: Hashimoto encephalitis is a diagnosis of exclusion in confused patients with autoimmune hypothyroidism and should be kept in mind as the prognosis is good with prompt steroid therapy. In this case, it was a part of a complex autoimmune syndrome. Presenting symptoms include confusion, seizures, psychosis and stroke like symptoms. There is no evidence of the pathogenic role of the thyroid antibodies and these are probably markers of some other autoimmune process affecting the brain.