Our patient is a twenty-four-year-old female with a sixteen-year history of HT-related hypothyroidism on oral levothyroxine 100 mcg once daily. She complained of occasional palpitations, nervousness, weight loss, and irregular menses. Thyrotoxicosis was confirmed with a thyroid function test, and levothyroxine dose was reduced. However, the patient continued to exhibit thyrotoxic symptoms even after completely stopping levothyroxine. On examination, the patient was calm but tachycardic and afebrile, and her blood pressure was 116/90 mmHg, weight was 58 kg, and BMI was 21.8. She was noted to have peripheral tremors. Her thyroid exam revealed the presence of diffuse nontender goiter, with no palpable nodules. Eye examination was only remarkable for mild exophthalmos, and there was no evidence of dermopathy.\nThyroid function revealed depressed TSH <0.01 mIU/L (0.3–4.2) and high T4 26.4 pmol/L (11.6–21.9) (). Based on the persistence of symptoms despite stopping thyroid hormone supplementations and the presence of ophthalmopathy elements, the rare shift to GD was suspected. Autoimmune workup revealed a strong positive Anti-TSH Receptor (Anti-TSHR) titer, in addition to persistent positivity of previously positive thyroid peroxidase antibody (TPO Ab) and an increasing titer of Antithyroglobulin Ab (). Thyroid ultrasound revealed slight enlargement of the right lobe and increased vascularity in both lobes. Radioactive iodine uptake scan (RAIU) showed diffuse radiotracer uptake more prominent in the right thyroid lobe (). Those findings kept with the shift to GD.\nThe patient received suppressive therapy with oral carbimazole 20 mg once daily and propranolol. A subsequent follow-up three months later showed normalization of thyroid function and improvement in clinical status.
46 years old female, mother of 3 children diagnosed as having primary hypothyroidism on the basis of clinical symptoms of easy fatigability, weight gain and increase sleep and a serum TSH level of >75 uIU/ml, FT4: 0.25 ng/dl and strongly positive thyroid antibodies in December 2002. Thyroxine 50 mcg/day was started which she continued. After 2 years she presented to us with complain of weight loss. Her serum TSH level was 0.035 uIU/ml and a T4: 7.84 ng/dl so thyroxine was stopped. She came for follow up after 5 months with serum TSH: 0.010 uIU/ml off thyroxine. After another 6 months her serum TSH remained suppressed with a value of 0.018 uIU/ml and an FT4 of 1.18 ng/dl and she remained off thyroxine. After further 2 years her TSH was 0.837 uIU/ml, FT4 0.922 ng/dl and FT3 3.06. And after 1 year she presented with a TSH level of <0.005 uIU/ml, raised FT4 and positive thyroid microsomal antibodies (1: 1600). Techniteum 99 thyroid scan showed diffusely increased homogenous tracer uptake. Neomercazole was started at the dose of 5 mg/day which was gradually increased to 10 mg/day. She followed up after 4 months with TSH: 0.01 uIU/ml, T4: 5.84 ng/dl, T3: 1.99 ng/dl. Neomercazole was continued. Then she came for follow up after 1 year, at this time she was clinically euthyroid but biochemically hypothyroid with serum TSH: 14.89 uIU/ml, FT4:0.65 ng/dl. Neomercazole was stopped and advised to repeat TFT’s after 8 weeks. She came after 4 months with TSH: 3.98 uIU/ml, so no treatment was advised. After a period of 1 year she again came with complains of weight loss and palpitations. At this time her TSH: < 0.005 uIU/ml, FT4: 2.25 ng/dl. Neomercazole was restarted and Radioactive iodine 131 ablation planned.