Endocrine Abstracts

Background: Autoimmune thyroid disease is a common cause of thyroid dysfunction, either Graves’ disease causing hyperthyroidism or Hashimoto’s thyroiditis causing hypothyroidism. It has been noted that patients suffering from autoimmune hypothyroidism can transform to hyperthyroidism and vice versa. We report the case of a patient with long standing autoimmune hypothyroidism presenting with active thyroid eye disease and subsequently diagnosed with Graves’ disease.

Case report: A 65-year-old woman with autoimmune hypothyroidism for 15 years presented with increasing eye symptoms. She complained of prominent eyes, and double vision. It had also been noted that her dose of thyroxine had been significantly decreasing. On examination, there was bilateral proptosis, restricted eye movement on upward gaze and palpable thyroid goitre and her clinical activity score was 3/7.

Blood test results showed TSH binding inhibitor immunoglobulin (TBII) 20.3 (high), FT₄ (13.4 pmol/l), FT3 (5.1 pmol/l) and TSH (0.14 mu/l), serial TFT’s showed suppressed TSH and normal FT3 and FT4. MRI showed excess intraorbital fat. Isotope scan showed increased activity in thyroid.

She was initially treated with a 3 day course of IV methylprednisolone followed by a reducing course of oral steroids and then another course of IV steroids. Her symptoms improved following the first course of IV steroids with clinical activity score of 1/7.

Discussion: This case illustrates that severe thyroid eye disease can present several years later from time of diagnosis of hypothyroidism and one suggested mechanism for transformation to Hashi toxicosis that the thyrotrophin receptor antibody has a heterogeneous function with stimulatory and inhibitory action.

Reference

1. Gupta MK. Thyrotrophin receptor antibodies: advances and importance of detection techniques in thyroid disease. Clin Biochem. 1992 193–199.