Graves' Ophthalmopathy in the Setting of Primary Hypothyroidism.

ABSTRACT

Graves' ophthalmopathy (GO) is commonly associated with hyperthyroidism secondary to Graves' disease (GD). Although rare, there have been case reports of it occurring in patients who are hypothyroid with underlying Hashimoto's thyroiditis (HT), as well as in euthyroid patients. Below, we describe a case of GO developing in a patient who has hypothyroidism secondary to HT successfully treated with high-dose steroids. We present a case of a 53-year-old female known to have primary hypothyroidism (Hashimoto's thyroiditis) diagnosed at the age of 39 years and has been on levothyroxine since diagnosis. She presented to our endocrine clinic complaining of new-onset diplopia and periorbital swelling for five months. There is no previous hyperthyroid state or radioactive iodine therapy. Examination showed left-sided upper and lower eyelid swelling, limited abduction with diplopia, and mild punctate keratopathy. Laboratory investigation revealed positive thyroid-stimulating immunoglobulin of 500 IU/mL (normal value <140 IU/mL) with thyroid-stimulating hormone (TSH) and free thyroxine (FT4) in the euthyroid range. She was found to have a small heterogeneous thyroid gland on ultrasound suggestive of atrophic thyroiditis, and magnetic resonance imaging (MRI) of the orbits demonstrated bilateral ocular proptosis with extraocular muscle enlargement. The patient was diagnosed with active moderate-severe isolated GO with a background of HT, clinically and biochemically euthyroid on levothyroxine. She was referred to an ophthalmologist and was started on a course of high-dose oral prednisone tapered over three months, which was followed by oral selenium and botox injections to both medial recti muscles. Graves' ophthalmopathy is an uncommon presentation in hypothyroid and euthyroid patients but should be considered in the differential diagnosis. The incidence varies between studies from 2% to 7.5%. Awareness of this clinical presentation is important, as early detection and treatment can prevent visual complications. To date, there are no clear guidelines on how to treat GO with underlying HT. Treating our patient with high-dose steroids extrapolated from treating GO secondary to GD showed significant improvement in her symptoms.