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Indications - As replacement therapy in hypothyroidism of any aetiology. Replacement therapy should not be instituted in transient hypothyroidism during the recovery phase of subacute Thyroiditis. For the suppression of Thyroid Stimulating Hormone (TSH) levels in the presence of goitres, nodules and after radiological and/or surgical treatment of Thyroid cancer. For the suppression of the goitrogenic effects of other drugs such as Lithium. As a diagnostic aid in suppression tests.

Dosage & Administration - Adult dose: Initial starting dose: 25-50 meg/day, with gradual increments in dose at 6-8 week intervals, as needed. The Levothyroxine Sodium dose is generally adjusted in 12.5-25 meg increments until the patient with primary hypothyroidism is clinically euthyroid and the serum TSH has normalized. In patients with severe hypothyroidism: Initial dose is 12.5-25 meg/day with increases of 25 meg/day every 2-4 weeks, accompanied by clinical and laboratory assessment,until the TSH level is normalized. In patients with secondary (pituitary) or tertiary (hypothalamic) hypothyroidism: Levothyroxine Sodium dose should be titrated until the patient is clinically euthyroid and the serum free - T4 level is restored to the upper half of the normal range. For patients older than 50 years or for patients under 50 years of age with underlying cardiac disease: 1.7 meg/kg/day. Pediatric Dosage (Newborns): The recommended starting dose is 10-15 meg/kg/day. A lower starting dose should be considered in infants at risk for cardiac failure and the dose should be increased in 4-6 weeks as needed based on clinical and laboratory response to treatment. In infants with very low (<5 mcg/dL) or undetectable serum T4 concentrations, the recommended initial starting dose is 50 meg/day of Levothyroxine Sodium. Pediatric Dosage (Infants and Children): In children with chronic or severe hypothyroidism, initial dose of 25 meg/day with increments of 25 meg every 2-4 weeks until the desired effect is achieved. Hyperactivity in an older child can be minimized if the starting dose is one-fourth of the recommended full replacement dose and the dose is then increased on a weekly basis by an amount equal to one-fourth the full recommended replacement dose until the full recommended replacement dose is reached. 0-3 months: 10-15 meg/kg/day 3-6 months: 8-10 meg/kg/day 6-12 months: 6-8 meg/kg/day 1-5 years: 5-6 meg/kg/day 6-12 years: 4-5 meg/kg/day >12 years but growth and puberty incomplete: 2-3 meg/kg/day Growth and puberty complete: 1.7 meg/kg/day. The dose should be adjusted based on clinical response and laboratory parameters.

Side Effects - Adverse reactions associated with Levothyroxine therapy are primarily those of hyperthyroidism due to therapeutic overdose. They include the following: General: Fatigue, increased appetite, weight loss, heat intolerance, fever, excessive sweating; Central nervous system: Headache, hyperactivity, nervousness, anxiety, irritability, emotional lability, insomnia. Musculoskeletal: Tremors, muscle weakness. Cardiovascular: Palpitations, tachycardia, arrhythmias, increased pulse and blood pressure Respiratory: Dyspnea. Gastrointestinal: Diarrhea, vomiting, abdominal cramps. Dermatologic: Hair loss, flushing.

Contraindications - Untreated subclinical or overt Thyrotoxicosis of any etiology Acute Myocardial Infarction Uncorrected Adrenal failure.

Others - Pregnancy & Lactation Pregnancy Category A. Pregnancy may increase Levothyroxine requirements. Although Thyroid hormones are excreted only minimally in human milk,caution should be exercised when it is administered to a nursing woman.However, adequate replacement doses of Levothyroxine are generally needed to maintain normal lactation.