evidence: This information is important because it means that if you have low thyroid function there’s a HIGH probability that it’s from Hashimoto’s, whether you realize it or not. [...] Hashimoto’s does NOT result in long-term hyperthyroidism so your symptoms will always eventually go back to hypothyroidism. [...] Patients with end-stage Hashimoto’s are REQUIRED to be on thyroid hormone for the rest of their lives because their own thyroid gland no longer functions to produce it.