Endocrine Abstracts

Subclinical hyperthyroidism is defined as low serum thyroid stimulating hormone (TSH) in the setting of normal levels of free T4 (fT4) and free T3 (fT3). Treatment for subclinical hyperthyroidism can be considered when TSH is persistently <0.1, particularly in (i) the presence of hyperthyroid symptoms, (iii) individuals aged >65 years, (iii) the presence of heart disease or osteoporosis. We present a case of a 34-year-old lady who was referred to endocrine outpatient clinic in view of neck swelling and subclinical hyperthyroidism. At presentation, the patient complained of recent weight loss and episodic palpitations. She had regular menses and denied any history of diarrhoea, tremor, anxiety, night sweats or hair loss. Neck examination revealed a palpable right thyroid nodule. There were no thyroid bruits. She was clinically euthyroid and there were no signs of dysthyroid eye disease. Thyroid profile sampling confirmed subclinical hyperthyroidism: TSH 0.013 mIU/L (0.3–3), fT4 16.07 pmol/L (11–18), fT3 6.5 pmol/L (3.5–6.5). TSH Receptor Antibody (TRAb) and anti-thyroid peroxidase antibody (TPOAb) titres were normal (TRAB 0.64 U/l [<1.8]; TPOAb < 10.0 iu/ML [0.0–50.0]). An ultrasound of the thyroid confirmed the presence of a 24 × 12 mm well-defined nodule in the right thyroid lobe, with internal vascularity on Doppler. An US guided aspiration had already been performed confirming a benign nodule (Thyroid Bethesda category 2). An NM Thyroid scan confirmed the occurrence of a large, well-defined focus of avid tracer uptake corresponding to the right thyroid nodule. The rest of the thyroid gland was hardly evident. This was consistent with a diagnosis of toxic adenoma in the context of subclinical hyperthyroidism. The patient was started on Carbimazole 5 mg daily on account of her symptomatology, rendering her euthyroid within a few weeks, and treatment options were discussed at length. The patient opted for thyroid lobectomy and has been referred for surgery.