Usual Adult Dose for Hypothyroidism

Mild Hypothyroidism:

• Initial dose: 25 mcg orally once a day; may be increased by up to 25 mcg every 1 or 2 weeks
• Maintenance dose: 25 to 75 mcg/day

Congenital Hypothyroidism:

• Initial dose: 5 mcg orally once a day; increase in 5 mcg per day increments every 3 to 4 days until desired response is achieved

Use: For use as replacement or supplemental therapy in patients with hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis; this category includes cretinism, myxedema, and ordinary hypothyroidism in patients of any age (pediatric patients, adults, the elderly), or state (including pregnancy); primary hypothyroidism resulting from functional deficiency, primary atrophy, partial or total absence of thyroid gland, or the effects of surgery, radiation, or drugs, with or without the presence of goiter; and secondary (pituitary) or tertiary (hypothalamic) hypothyroidism

Usual Adult Dose for Myxedema

Initial dose: 5 mcg orally once a day

• Following initial dose: May be increased by 5 to 10 mcg per day every 1 or 2 weeks; when 25 mcg/day is reached, dose may be increased by 5 to 25 mcg every 1 to 2 weeks until satisfactory response is attainted

Maintenance dose: 50 to 100 mcg/day

Usual Adult Dose for Myxedema Coma

Initial dose: 25 to 50 mcg IV once

Patients with known or suspected cardiovascular disease:

• Initial dose: 10 to 20 mcg IV once

Comments:

• Initial and subsequent doses should be based on continuous monitoring of the patient's clinical condition and response to therapy.
• At least 4 hours should be allowed between doses to adequately assess response and no more than 12 hours should elapse between doses to avoid fluctuations in hormone levels.
• Exercise caution when adjusting dose due to potential of large changes to precipitate adverse cardiovascular events.
• Decreased mortality has been reported in patients receiving at least 65 mcg/day in the initial days of treatment; however, limited clinical experience with total daily doses above 100 mcg.

Use: For the treatment of myxedema coma/precoma

Usual Adult Dose for Thyroid Suppression Test

75 to 100 mcg orally per day for 7 days

Comments:

• Radioactive iodine uptake is determined before and after administration of the thyroid hormone.
• If thyroid function is under normal control, the radioiodine uptake will drop significantly after treatment.
• Administer cautiously to patients in whom there is a strong suspicion of thyroid gland autonomy, in view of the fact that the exogenous hormone effects will be additive to the endogenous source.

Use: For use as a diagnostic agent in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy

Usual Adult Dose for Goiter

Initial dose: 5 mcg orally once a day

• Following initial dose: Increase by 5 to 10 mcg per day every 1 or 2 weeks; when 25 mcg/day is reached, dose may be increased by 12.5 or 25 mcg per day every 1 to 2 weeks until satisfactory response is attainted

Maintenance dose: 75 mcg orally once a day

Use: For use as pituitary thyroid-stimulating hormone (TSH) suppressants, in the treatment or prevention of various types of euthyroid goiters, including thyroid nodules, subacute or chronic lymphocytic thyroiditis (Hashimoto's) and multinodular goiter

Usual Adult Dose for TSH Suppression

Initial dose: 5 mcg orally once a day

• Following initial dose: Increase by 5 to 10 mcg per day every 1 or 2 weeks; when 25 mcg/day is reached, dose may be increased by 12.5 or 25 mcg per day every 1 to 2 weeks until satisfactory response is attainted

Maintenance dose: 75 mcg orally once a day

Use: For use as pituitary thyroid-stimulating hormone (TSH) suppressants, in the treatment or prevention of various types of euthyroid goiters, including thyroid nodules, subacute or chronic lymphocytic thyroiditis (Hashimoto's) and multinodular goiter

Usual Geriatric Dose for Hypothyroidism

Initiate at 5 mcg orally once a day and increase by no more than 5 mcg increments at 2 week intervals

Use: For use as replacement or supplemental therapy in patients with hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis; this category includes cretinism, myxedema, and ordinary hypothyroidism in patients of any age (pediatric patients, adults, the elderly), or state (including pregnancy); primary hypothyroidism resulting from functional deficiency, primary atrophy, partial or total absence of thyroid gland, or the effects of surgery, radiation, or drugs, with or without the presence of goiter; and secondary (pituitary) or tertiary (hypothalamic) hypothyroidism

Usual Pediatric Dose for Hypothyroidism

Congenital Hypothyroidism:

• Initial dose: 5 mcg orally once a day; increase in 5 mcg per day increments every 3 to 4 days until desired response is achieved
• Maintenance dose: Infants a few months old may require only 20 mcg/day for while patients at 1 year may require 50 mcg/day; above 3 years, the full adult dosage may be necessary.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

Switching from IV to oral therapy for the treatment of myxedema coma:

• Oral therapy should be resumed as soon as the clinical situation has been stabilized and the patient is able to take oral medication.
• Discontinue IV doses, initiate oral therapy at a low dosage, and increase gradually according to patient response.

Patients with cardiovascular disease receiving oral therapy: Initiate at 5 mcg orally once a day and increase by no more than 5 mcg increments at 2 week intervals

Precautions

US BOXED WARNING:

• TREATMENT OF OBESITY: Drugs with thyroid hormone activity, alone or together with other therapeutic agents, have been used for the treatment of obesity. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.

IV: Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• The oral tablets are recommended for once a day dosing.

Storage requirements:

• IV vials: Store between 2C and 8C (35F and 46F).

General:

• Dosing of thyroid hormones is determined by the indication and must be individualized according to patient response and laboratory findings.

Monitoring:

• Endocrine: Periodically obtain thyroid function tests.
• Genitourinary: Closely monitor urinary glucose levels in patients with diabetes while taking this drug.
• Hematologic: Frequent monitoring of prothrombin time should occur if concomitant anticoagulant therapy is used.

Patient advice:

• Report if at any point during the course of therapy any signs or symptoms of thyroid hormone toxicity, (e.g., chest pain, increased pulse rate, palpitations, excessive sweating, heat intolerance, nervousness), or any other unusual event.
• Partial hair loss may occur in pediatric patients during the first few months of treatment; however, this is usually transient.