Hyperthyroidism Times 2: Dual Cause of Thyroid Hormone Excess

Abstract

The most common etiology of Hyperthyroidism is due to circulating antibodies that are directed against the thyroid-stimulating hormone (TSH) receptor, known as Grave’s Disease (GD). Another cause is an autonomously functioning thyroid nodule over-producing hormones or Toxic Adenoma. The mechanism of these two pathologies are very distinct, but the question that arises is, can they coexist?This is a case of 44-year-old female who comes to the clinic referred by her ophthalmologist after been diagnosed with severe thyroid-associated orbitopathy currently on steroid therapy. Thyroid ultrasound has done previously showed enlarged homogenous thyroid gland with a single isoechoic nodule of 2.2x1.6x1.9cm with faint peripheral calcifications and vascularity. The patient was presenting with palpitations, heat intolerance, sweating, and discriminatory features such as double vision and left eye exophthalmos. On physical examination, there was no goiter or palpable thyroid nodules, but it was remarkable for left eyelid lag retraction and mild proptosis. Evaluation showed clinical and biochemical hyperthyroidism with TSH: 0.068 mU/ml (n:0.5-5.0mU/ml), FT4: 1.39ng/dl (n:0.87-1.85ng/dl), TSH receptor antibody: <1.10IU/L and thyroid-stimulating immunoglobulin: 0.54IU/L (borderline high). The patient was placed in antithyroid drugs and B-blockers for disease control. Afterward, the patient underwent a thyroid uptake scan reporting toxic adenoma on the left lobe, however even when the biochemical workup of GD is inconclusive, patient clinical findings are highly suggestive of it. Due to the risk of worsening orbitopathy with radioactive iodine therapy, patient was referred for surgical excision of toxic adenoma and total thyroidectomy was decided since residual thyroid tissue may expose the patient to circulating thyroid-stimulating immunoglobulin leading to hyperthyroidism recurrence and put her at risk of associated thyroid excess detrimental complications. Surgical specimen gross pathology biopsy reported the thyroid gland with hyperplastic changes of Grave’s Disease. Severe thyroid-associated orbitopathy was managed with decompression surgery but did not improve, for which an alternative therapeutic approach is decided with novel immunomodulatory agent and recent approved therapy, Teprotumumab. A monoclonal antibody that works on TSHR/IGF-1R signaling complex involved in Thyroid Eye Disease.Is unusual to see two different superimposing thyroid pathologies, but disease presentations can be atypical and can be present concomitantly. In this scenario, several factors must be taken into consideration when choosing an adequate therapy approach. Our case is an example that we need to individualize management options based on guidelines recommendations, patient’s clinical settings and decreased risks of future complications.