Periodic monitoring is essential in the management of patients with hypothyroidism to judge the clinical response to treatment, patient compliance in taking the medication, and development of drug interactions, and to adjust the replacement dosage because of changes in body weight or advancing age. Patients should be evaluated initially about every 6 to 8 weeks to monitor the response to the dose of levothyroxine. Once the TSH concentration has been normalized, the need for frequent visits is reduced. Visit frequency of every 6 to 12 months is then sufficient, depending on the clinical situation. Should it be necessary to adjust a patient's dosage, he or she should return in 2 to 3 months to assess the therapeutic response and to remeasure the TSH concentration.

An interim history should assess response to therapy with thyroid hormone, evaluating clinical improvement in symptoms, as well as possible side effects of the medication. A physical examination relevant to the thyroid status should be performed annually. A TSH concentration should be measured at least annually. For patients who have recently started receiving levothyroxine or who have had their dosage, type, or brand of thyroid preparation changed, the TSH concentration should be measured after 8 to 12 weeks.