Graves’ disease, an autoimmune disorder resulting in hyperthyroidism, can be associated with bulging eyes (exophthalmos) and a staring gaze (lid lag). Does overdose of levothyroxine cause the same signs?
Graves’ disease is an autoimmune disease involving production of antibodies against the thyroid-stimulating hormone (TSH) receptor (TSHR), also known as the thyrotropin receptor (Davies, 2017). The autoantibodies to the thyrotropin receptor (TRAb) activate TSHRs. In most patients this results in stimulation of thyroid hormone synthesis and secretion resulting in hyperthyroidism.
Hypothyroidism, for example caused by Hashimoto’s thyroiditis, is often treated with levothryoxine to replace the deficiency in endogenous thyroxine. Overdose of levothyroxine can cause hyperthyroidism.
But Graves’ disease is not synonymous with hyperthyroidism (Davies, 2017). Some patients produce TRAb but do not have hyperthyroidism and, by mechanisms independent of thyroid hormone secretion, TRAb can cause orbitopathy resulting in exophthalmos, and dermopathy due to pretibial myxoedema.