Case Studies

Following are the observations made by her endocrinologist :

Case History

• prominence of eyeballs since 2- 3 years
• puffiness of face and
• weight gain since 2 years.On inquiry

No history suggestive of hypothyroidism/ hyperthyroidism

No complaints of diplopia , blurring of vision, redness of eyes, pain or increased lacrimation.

No past h/o thyrotoxicosis.

No family h/o thyroid disorders

Obstetric history: Full term normal delivery 15 months back.

No Goitre

Eye Signs: Bilateral Proptosis( exophthalmos) class 3, was present.

No restriction of eye movements.

There was a marked delay in the relaxation of ankle jerks.

Rest of the Systemic Examination was normal.

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Provisional Diagnosis: Hypothyroidism with Autoimmune Ophthalmopathy On investigations :

Thyroid function tests were suggestive of Primary hypothyroidism ( T3- 35ng/dl; T4- 0.7 mg/dl; TSH- > 100mIU/ml). Antimicrosomal antibodies was markedly positive.

Patient was started on L- Thyroxine 100mg/day. Within 3 months she achieved euthyroid state ( T4- 14.7mg/dl, TSH - 0.6 mIU/ml). She followed up regularly for 2 years and was euthyroid during this period. However her ophthalmopathy did not worsen.

Discussion :

Thyroid ophthalmopathy(TO) is commonly present with Grave's Disease. It may be associated with hypothyroidism but the association is indeed rare. Grave's Disease is responsible in around 95% and Hashimoto's thyroiditis in around 5% of patients.

TO is considered to be an autoimmune response of the orbital tissues to abnormalities of the thyroid gland.

The working hypothesis is that the immune system recognises an antigen common to the thyroid and retro orbital tissues. Such antigens may be the same molecule or a molecule similar enough to be mistaken as the same antigen by the phenomenon of specificity crossover. Retro orbital fibroblast appear to be the primary site of this antigen. Expression of TSH Receptor mRNA by the retro orbital fibroblast has provoked speculation that TSH mRNA may be involved in the pathogenesis of orbitopathy.

In autoimmune thyroiditis about 10-20% of patients have TSHRAb( TSH receptor antibodies) while in Grave's disease their prevalence is 80- 95%.

Exophthalmos is usually bilateral and is often asymmetrical. True unilateral exophthalmos is uncommon. The degree of exophthalmos must be measured objectively with the Hertel or Luedde exophthalmometer.

Other diseases that may produce either unilateral or bilateral exophthalmos include orbital neoplasms, carotid-cavernous sinus fistulae, cavernous sinus thrombosis, infiltrative disorders affecting the orbit and pseduotumor of the orbit.

The treatment aims at correction of Hypothyroidism by starting L- Thyroxine. The management of exophthalmos is similar to that associated with Graves toxicosis: steroids, retro-orbital radiotherapy or orbital decompression depending on the severity.

Prepared by Dr. Nikhil Bhagwat & Dr. Padma S. Menon,

from the Department of Endocrinology, KEM Hospital & Seth GS Medical College, Parel, Mumbai, 400 012.