**2. Epidemiology and pathogenesis**

The peak incidence of GD is observed between 30 to 50 years of age. Annual reported incidence of GD is 50 and of ophthalmopathy is 16 per 100000 population. Orbital imaging if performed in all patients of GD will reveal changes of ophthalmopathy in upto 70% of patients. Approximately 3% of women and 0.5% of men during their life time can develop GD [6].

GD is an organ specific auto immune disease caused by thyroid stimulating hormone receptor (TSHR) circulating stimulating auto antibodies. The TSHR stimulating antibody binds to leucine rich extracellular domain of TSHR on surface of thyrocytes and orbital fibroblasts and IGF1 receptors. After binding it increases production of intracellular cyclic AMP causing thyrocyte growth and increased thyroid hormone production.
