Fluctuating Grave's Disease and Hashimoto's Thyroiditis: A Case Report

Graves' disease and Hashimoto's thyroiditis are two distinct autoimmune entities with different pathophysiology and treatment. However, they can fluctuate in the same patient at other times. This study aims to present the case of a patient who converted to hyperthyroidism from chronic hypothyroidism and how she was treated.

Case Description:

A 54-year-old woman was referred to the Endocrine clinic with thyroid disease. She was initially diagnosed with hypothyroidism 12 years ago. She was doing well on levothyroxine replacement therapy for about ten years when she developed left eye proptosis. Laboratory investigations revealed a suppressed thyroid-stimulating hormone with a positive thyroid-stimulating immunoglobulin (TSI) level. Levothyroxine replacement was discontinued, and she was followed with repeat laboratory investigations. Treatment for Graves’ disease was initiated when she remained hyperthyroid months after stopping thyroxine replacement.

Discussion:

Autoimmune thyroid disease can lead to an over-functioning or hyperfunctioning thyroid gland. Most people have one or the other autoimmune thyroid disease. Since patients with autoimmune thyroid disease can have both thyroid peroxidase antibodies and TSI, they can manifest either way and occasionally alternate between two distinct disease states. Some patients can have fluctuating Graves’s disease and Hashimoto’s thyroiditis leading to an unpredictable disease course. Clinicians need to be aware of this possibility to avoid exacerbation of thyrotoxicosis with thyroxine replacement in a hypothyroid patient who presents with suppressed TSH and signs or symptoms of Graves’ disease.