Can hyperthyroidism come and go?

Fluctuate.: Most common cause of hypothyroidism is hassimoto's thyroiditis. It makes the thyroid function fluctuate at the early disease state.

Not usually: Medical therapy sometimes can not keep hyperthyroidism entirely controlled and can be peaks and valleys of overproduction of hormone.. Autoimmune thyroiditis, Inflammation of gland, can have hyperactive, normal, and hypothyroid phases