Endocrine Abstracts

Background: Thyroid dysgenesis (TD) represents a heterogeneous group of conditions and accounts for 85% of cases of congenital hypothyroidism (CH). This can be due to abnormal gland organogenesis which results in thyroid agenesis (35–40% of the cases), thyroid hypoplasia (5%) and thyroid ectopy (30–45%).

Causes of CH can be classified into: one. dyshormonogenesis usually associated with goiter, caused by mutations in the genes coding for the proteins responsible for thyroid hormone synthesis; two. dysembryogenesis or dysgenesis, that may be due to: i) inactivating TSHR mutations; ii) genetic mutation affecting the thyroid transcription factors.

We report a case of 54 years old lady who presented to our endocrine clinic with hypothyroidism on thyroxine replacement, sensorineural hearing loss, short stature (9°centile) and obesity (BMI 40.3). She did not have any learning difficulties. She was diagnosed hypothyroid at 14 years of age. She had no significant past medical or family history. Her thyroxine was stopped for 3 weeks and investigations were carried out. She tolerated discontiuation of thyroxine well. Her TSH was 84.6 mU/l (0.4–5.0), FT₄ was 4.9 pmol/l (10–23) and FT₃ was 1.6 pmol/l (3.5–6.5) suggesting primary hypothyroidism. She was also found to have GH deficiency on provocative test. Thyroid uptake scan revealed absent thyroid gland. MRI of the pituitary showed normal gland. In view of deafness CT scan of the inner ear was done and it was normal. Genetic test for Pendred syndrome was negative. She has been started on thyroxine and GH replacement.

Interpretation: We report a case of primary hypothyroidism due to hypoplastic/absent thyroid tissue associated with GH deficiency, sensorineural deafness and normal mental development. Familial occurrence of GH deficiency and primary hypothyroidism has been reported in three male siblings in the literature but thyroid absence with GHD has not been reported to our knowledge.