Endocrine Abstracts

We present the case of a 22-year-old male patient who posed a diagnostic dilemma due to discrepancies between his symptoms and biochemical markers in contrast to imaging findings. He reported a 18 month history of on and off neck swelling with associated symptoms of anxiety, tremor, loose stools and dry eyes (no weight loss). Thyroid function tests were normal with a Free T4 (FT4) of 12.4 pmol/l (12-22 pmol/l), TSH 2.75mU/l (0.27-4.2mU/l) and an ultrasound showed an enlarged and hypervascular thyroid gland. Subsequent investigations revealed a Low Free T4 (FT4) of 11.3 pmol/l (12-22 pmol/l), Normal FT3 = 5.1 pmol/l and TSH 1.07mU/l, TSH receptor antibody (TRAb) < 0.8 IU/l, Thyroid peroxidase antibody (anti-TPO) < 9 IU/ml and normal thyroglobulin antibodies at 11 IU/l (range 0 to 115). Subsequent antibody titres showed negative TRAb, Thyroid peroxidase antibody (anti-TPO) < 1.0 IU/ml and undetectable thyroglobulin antibodies. Thyroid ultrasound indicated an enlarged gland with increased vascularity. A Tc-99m pertechnetate thyroid scan showed diffusely increased uptake (13.9%). He responded well to beta-blockade for symptom control (past history of Asthma and mild neutropenia noted). Upon one-year follow-up, the patient continued symptom free with beta-blockade, albeit with subjective eye symptoms but no objective signs of thyroid eye disease. Investigations were repeated at this stage: FT4 remained low 10.9 pmol/l (12-22 pmol/l), FT3 5.8 pmol/l (3.1-6.8 pmol/l), TSH 1.3mU/l (0.27-4.2mU/l). The FT4:FT3 ratio was 1.8 (in keeping with an active process, rather than thyroiditis). Antibodies including anti-TPO, anti-thyroglobulin and TRAb again tested negative. Repeat Thyroid ultrasound revealed a swollen lobulated gland with mildly increased vascularity and pertechnetate thyroid scan showed significant and diffusely increased uptake (23.1%). We thus see no changes in the thyroid status with normal TSH, TRAb, thyroid antibodies in contrast to the radiological evidence of hyperactivity. In conclusion, this case underscores the complexities in diagnosing thyroid disorders with unique differential diagnoses of with a subclinical hyperactive (periodic) Graves’, early stage of chronic autoimmune thyroiditis (CAT); or less commonly congenital thyroid hormone synthesis defects or iodine deficiency. Discussion points include a Serial monitoring over two years showed no progression in imaging or uptake characteristics, making CAT less probable. He being symptomatic for less than 2 years makes congenital defects less likely. Use of I-123 and performing a perchlorate discharge test could identify rare organification defects. Lastly TRAb negative Grave’s disease is still a possibility. However serial follow-up has not revealed a worsening picture or signs of abating, which makes this diagnosis less likely.