Primary hypothyroidism preceding thyrotoxicosis: a report of 2 cases and a review of the literature.

Two cases are reported in whom primary hypothyroidism preceded thyrotoxic Graves' disease. The hypothesis is advanced that this sequence of events was mediated by spontaneous changes in the patient's autoimmune reactions to thyroid. In particular, it may reflect a spontaneous alteration in the balance between blocking antibodies reactive at or near the TSH receptor or cytotoxic thyroid autoimmune mechanisms on the one hand, and thyroid stimulating autoantibodies on the other.