When people are treated for hyperthyroidism they sometimes develop hypothyroidism – an underactive thyroid. This is because the medication causes the thyroid to go from overactive to underactive if the correct dose is not taken.

What causes hyperthyroidism to change to hypothyroidism?

Over time the thyroid usually returns to its normal state. Because the stored thyroid hormone has been released, patients may become hypothyroid (where their thyroid gland produces too little thyroid hormone) for a period of time until the thyroid gland can build up new stores of thyroid hormone.

Can thyroid fluctuate between hyper and hypo?

Alternating between hyper- and hypo-thyroidism may be explained by the simultaneous presence of both types of TSH receptor autoantibodies (TRAbs) – thyroid stimulating autoantibodies (TSAbs) and TSH blocking autoantibodies (TBAbs). It is a very rare condition, particulary in the pediatric age.