Patient presents with symptoms consistent with hypothyroidism, including fatigue, weight gain, constipation, cold intolerance, dry skin, and hair loss.  These symptoms have been progressively worsening over the past six months.  Physical examination reveals bradycardia, dry skin, and a mildly enlarged, non-tender thyroid gland.  Laboratory results demonstrate elevated thyroid stimulating hormone (TSH) levels and low free thyroxine (T4).  Thyroid peroxidase antibodies (TPOAb) are positive, confirming the diagnosis of Hashimoto's thyroiditis, an autoimmune disorder causing hypothyroidism.  Differential diagnoses considered included iodine deficiency and central hypothyroidism, but were ruled out based on laboratory findings and clinical presentation.  The patient's medical history is significant for hypertension, managed with lisinopril.  Family history is positive for autoimmune disorders.  Assessment: Primary hypothyroidism secondary to Hashimoto's thyroiditis.  Plan: Initiate levothyroxine therapy, starting at a low dose with gradual titration based on TSH levels and clinical response.  Patient education provided regarding medication management, potential side effects, and the importance of regular monitoring.  Follow-up appointment scheduled in six weeks to reassess thyroid function and adjust medication dosage as needed.  ICD-10 code: E03.1  Hashimoto's thyroiditis with hypothyroidism.  Medical billing codes will reflect evaluation and management services, laboratory testing, and medication management.