Hashimoto's disease progresses through five stages with different symptoms and levels of thyroid hormone production. Stage 1: The thyroid gland is enlarged and produces too much hormone, leading to symptoms such as weight issues, anxiety, and heart palpitations. Stage 2: The thyroid gland begins to produce less hormone, causing symptoms such as fatigue, depression, and weight gain. Stage 3: The thyroid gland becomes damaged and the body's immune system starts attacking it. Symptoms may include a goiter (enlarged thyroid gland) and difficulty swallowing. Stage 4: The thyroid gland continues to be damaged which ultimately leads to hypothyroidism (low thyroid hormone production). Symptoms include fatigue, weight gain, constipation, and dry skin. Stage 5: The most severe stage of Hashimoto's disease occurs when the thyroid gland is almost completely destroyed and the body produces none or very little thyroid hormone. Symptoms include extreme fatigue, weight gain, hair loss, and cold intolerance.