Endocrine Abstracts

Introduction

We present the case of a 50-year-old lady who was referred to the endocrine clinic with a clinical and biochemical picture suggestive of severe thyrotoxicosis. CT scan of thorax, abdomen and pelvis (CT TAP) was performed to rule out malignancy, which showed left lobe agenesis.

Case

50-year-old lady presented to the GP with hyperhidrosis and unintentional weight loss. She also reported symptoms of lethargy, increased bowel frequency, tinnitus, periorbital oedema, cold insensitivity, oligomenorrhoea, palpitations, essential tremor and irritability. She had a background of asthma and depression with a maternal history of hypothyroidism. Initial TFTs showed severe thyrotoxicosis which was sustained when repeated 6 weeks later in the endocrine clinic. Thyroid peroxidase antibodies and TSH receptor antibodies were positive which confirmed the diagnosis of Grave’s disease. CT TAP was arranged through primary care to rule out malignancy and incidentally showed a missing left lobe of the thyroid but intact isthmus and right lobe. There was no previous history of thyroidectomy so a diagnosis of thyroid hemiagenesis (THA) was made. The patient was treated with carbimazole with a good response and this is being titrated based on her 6 weekly TFTs.

Discussion

THA is a rare, congenital developmental disorder of the thyroid gland, characterised by the absence of one thyroid lobe. The exact aetiology is unknown but there are several theories based on embryological descent and lobulation, development of blood vessels, and genetic factors. The majority of cases have an absent left lobe. Absence of one lobe of the thyroid usually has no clinical significance and patients are usually biochemically euthyroid and asymptomatic. However, reports have shown that patients with THA are more likely to develop thyroid disorders with hyperthyroidism being the most common clinical presentation. Patients with THA are generally asymptomatic and diagnosis is often incidentally made on routine clinical examinations or imaging modalities. There is also a 7:1 female to male ratio of THA which indicates a possible gender association. Our case is a typical presentation of THA as we had a female patient with a missing left lobe with features of thyrotoxicosis. The aim of treatment in THA is to correct any thyroid hormone imbalance; medically or surgically, manage symptoms and prevent recurrence.