A 29-year-old pregnant lady known hypothyroid for 5 years, presented with thyroid eye disease (TED). She is a non-smoker. Her TFT in the past years has been stable.
Her exophthalmos was noticed at early pregnancy. Her anti-thyroid peroxidise antibodies (TPO-Ab) were >1300 mU/l (ref. range <1.4) and TSH-R antibodies (TRAB) were 18.6 U/l (ref. range <5.0).
On presentation she was clinically and biochemically euthyroid with no ophthalmic complaints. She had bilateral exophthalmos. There was lid retraction but no lid lag, diplopia, peri-orbital oedema or visual field deficit. She had a smooth goitre.
Her levothyroxine was increased to 125 μg and dropped back near delivery.
She delivered a healthy baby in August 2009 with normal TFT and negative TPO-Abs (TRAB not tested by the obstetricians).
Discussion: Thyroid eye disease is technically known as Gravess ophthalmopathy. Clinical TED with TRAB positive is likely autoimmune. However there are reports of TED in Hashimoto thyroiditis, thyroid cancer and euthyroid eye disease. The pathophysiology of TED likely involves genetic and environmental factors, which may potentiate cellular and humoral-mediated inflammation within the orbit. A unifying hypothesis of TED pathophysiology is elusive.
Our patient has Hashimoto thyroiditis with TRAB positive TED. It is likely that similar autoimmune mechanisms, as in Graves, are behind the Hashimotos thyroiditis eye disease, contributed in part by the TRAB. It is possible that other antibodies have a major role to play in TED, irrespective of the thyroid status. This would explain the dichotomy seen in TED with and without TRAB positivity and TED with various thyroid diseases.
Our case illustrates the notion that TED could be present in any autoimmune thyroid disorder, irrespective of the nature of the antibodies present. Further research is needed to look at other etiological factors, which might explain the dichotomy.