Pituitary Thyrotropin (Thyroid-Stimulating Hormone, TSH) Suppression

CYTOMEL is indicated as an adjunct to surgery and radioiodine therapy in the management of well-differentiated thyroid cancer.

Thyroid Suppression Test

CYTOMEL is indicated as a diagnostic agent in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy.

Limitations of Use

• CYTOMEL is not indicated for suppression of benign thyroid nodules and nontoxic diffuse goiter in iodine-sufficient patients as there are no clinical benefits and overtreatment with CYTOMEL may induce hyperthyroidism [see Warnings and Precautions (5.4)].
• CYTOMEL is not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.

DOSAGE AND ADMINISTRATION

General Principles of Dosing

The dose of CYTOMEL for hypothyroidism or pituitary Thyroid-Stimulating Hormone (TSH) suppression depends on a variety of factors including: the patient's age, body weight, cardiovascular status, concomitant medical conditions (including pregnancy), concomitant medications, co-administered food and the specific nature of the condition being treated [see Dosage and Administration (2.2, 2.3, 2.4), Warnings and Precautions (5), and Drug Interactions (7)]. Dosing must be individualized to account for these factors and dose adjustments made based on periodic assessment of the patient's clinical response and laboratory parameters [see Dosage and Administration (2.4)].

Administer CYTOMEL tablets orally once daily.

Recommended Dosage for Hypothyroidism

Adults

The recommended starting dosage is 25 mcg orally once daily. Increase the dose by 25 mcg daily every 1 or 2 weeks, if needed. The usual maintenance dose is 25 mcg to 75 mcg once daily.

For elderly patients or patients with underlying cardiac disease, start with CYTOMEL 5 mcg once daily and increase by 5 mcg increments at the recommended intervals.

Serum TSH is not a reliable measure of CYTOMEL dose adequacy in patients with secondary or tertiary hypothyroidism and should not be used to monitor therapy. Use the serum T3 level to monitor adequacy of therapy in this patient population.

Pediatric Patients

The recommended starting dosage is 5 mcg once daily, with a 5 mcg increase every 3 to 4 days until the desired response is achieved. Infants a few months old may require 20 mcg once daily for maintenance. At 1 year of age, 50 mcg once daily may be required. Above 3 years of age, the full adult dosage may be necessary [see Use in Specific Populations (8.4)].

Newborns (0 to 3 months) at Risk for Cardiac Failure:

Consider a lower starting dose in infants at risk for cardiac failure. Increase the dose as needed based on clinical and laboratory response.

Pediatric Patients at Risk for Hyperactivity:

To minimize the risk of hyperactivity in pediatric patients, start at one-fourth the recommended full replacement dose, and increase on a weekly basis by one-fourth the full recommended replacement dose until the full recommended replacement dose is reached.

Pregnancy

Pre-existing Hypothyroidism: Thyroid hormone dose requirements may increase during pregnancy. Measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range. For patients with serum TSH above the normal trimester-specific range, increase the dose of thyroid hormone and measure TSH every 4 weeks until a stable dose is reached and serum TSH is within the normal trimester-specific range. Reduce thyroid hormone dosage to pre-pregnancy levels immediately after delivery and measure serum TSH levels 4 to 8 weeks postpartum to ensure thyroid hormone dose is appropriate.