Thyroid-stimulating antibody in a patient with euthyroid Graves' disease

Area of Science:

• Endocrinology
• Pediatric Endocrinology
• Ophthalmology

Background:

• Graves' disease typically presents with hyperthyroidism.
• Euthyroid Graves' disease is a variant where thyroid hormone levels are normal.
• Ocular manifestations like exophthalmos can occur even without overt hyperthyroidism.

Observation:

• An 11-year-old girl presented with unilateral exophthalmos and subnormal thyroid-stimulating hormone (TSH).
• Initial thyroid function tests (free thyroxine and free triiodothyronine) were normal.
• Positive anti-TSH receptor antibody (TRAb) and thyroid-stimulating antibody (TSAb) were detected at low titers.

Findings:

• The patient later developed hyperthyroidism, confirmed by elevated thyroid hormones.
• Treatment with propylthiouracil resolved hyperthyroid symptoms.
• Thyroid-stimulating antibody (TSAb) remained positive after TRAb became negative, indicating its persistence.

Implications:

• Thyroid-stimulating antibody (TSAb) is a valuable diagnostic and monitoring marker for euthyroid Graves' disease.
• Measurement of TSAb is recommended for children presenting with unexplained exophthalmos.
• This case highlights the importance of considering TSAb in diagnosing atypical presentations of Graves' disease.