Endocrine Abstracts

Introduction: Graves’ disease and Hashimoto’s thyroiditis are the two autoimmune spectrum of thyroid disease. Cases of conversion from hyperthyroidism to hypothyroidism have been reported but conversion from hypothyroidism to hyperthyroidism is very rare although reported. We report a case of hypothyroidism that converted to a hyperthyroid state needing treatment.

Case report: A 36 years old female presented with a 3 months history of easy fatigability, cold intolerance, polymenorrhagia, constipation and weight gain. On examination she hadbradycardia and dry skin. Thyroid gland showed small diffuse enlargement. Clinical suspicion of primary hypothyroidism was made and thenconfirmed by TSH of >50 uIU/ml (0.4–4.2 uIU/ml) with FT₄ value of <0.30 ng/dl and positive thyroid antibody titre. Thyroxine was started at 100 μg/day. Gradually requirement of thyroxine decreased and she maintained her TSH within normal range on 50 μg/day of thyroxine. After 3 years dose was further reduced to 25 μg/day but after 2 years again thyroxine dose was increased to 50 μg/day because of slightly increased TSH of 8.86. Slightly more than a year later she presented with weight loss of 3 kg and feeling of anxiety and tremors of hands. TSH was <0.005 with a FT₄ of 2.4 confirming the state of thyrotoxicosis. Thyroxine was stopped and patient was observed over a period of 6 months. She remained clinically and biochemically hyperthyroid with a repeat TSH of <0.005 and FT₄ of 2.66. Thyroid scintigraphy showed an increased homogenous tracer uptake. She was started on Carbimazoleand she remains on it till date.

Conclusion: This case demonstrate that high index of suspicion should be there if a patient with primary hypothyroidism develop persistent symptoms of hyperthyroidism. Otherwise it can be missed easily considering it as an over replacement with thyroid hormone.