Hello, thank you for putting your trust in our site, my name is Dr.Soliman and I will be glad to answer your question. Hashimoto thyroiditis is an autoimmune disease in which the immune system attack the cells of the thyroid gland leading to under active thyroid or hypothyroidism. There is definite timeline to when to expect to experience the symptoms of hypothyroidism and probably you may not experience any symptoms if the thyroid gland is still active and not affected by the disease. the most common symptoms of hypothyroidism that you may acquire are; Fatigue and sluggishness, increased sensitivity to cold, Constipation, pale, dry skin, a puffy face, brittle nails, hair loss, enlargement of the tongue, unexplained weight gain, muscle aches, tenderness and stiffness, joint pain and stiffness, muscle weakness. If Hashimoto s disease causes thyroid hormone deficiency, you may need replacement therapy with thyroid hormone. This usually involves daily use of the synthetic thyroid hormone levothyroxine (Levoxyl, Synthroid, others). Treatment with levothyroxine is usually lifelong, but because the dosage you need may change, your doctor is likely to check your TSH level about every 12 months. I hope this answer fulfill your query and if you are satisfied with the answer please consider giving 5 star rating , and feel free to ask any additional questions and I will gladly help you with an answer.