Patient presents with complaints consistent with Hashimoto's thyroiditis, including fatigue, weight gain, constipation, dry skin, and cold intolerance.  Symptoms onset was reported as gradual over the past several months.  Physical examination revealed a mildly enlarged, non-tender thyroid gland.  Laboratory findings demonstrate elevated thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb), confirming the diagnosis of Hashimoto's disease.  TSH levels are elevated, while free T4 levels are within normal range or low, indicating subclinical or overt hypothyroidism.  Patient denies any history of neck irradiation or family history of thyroid cancer.  Differential diagnosis considered hypothyroidism from other causes, iodine deficiency, and thyroid nodules.  Assessment includes autoimmune thyroiditis, Hashimoto's disease, and hypothyroidism.  Plan includes initiation of levothyroxine therapy, titrated to normalize TSH and alleviate symptoms.  Patient education provided regarding the chronic nature of Hashimoto's, the importance of medication adherence, and the need for ongoing monitoring of thyroid function tests.  ICD-10 code E03.1, hypothyroidism due to autoimmune thyroiditis, is documented.  Follow-up appointment scheduled in six to eight weeks to assess response to therapy and adjust levothyroxine dosage as needed.  Discussion included potential side effects of levothyroxine and the importance of reporting any new or worsening symptoms.