• Initial starting dose: 25-50 mcg/day, with gradual increments in dose at 6-8 week intervals, as needed. The Levothyroxine Sodium dose is generally adjusted in 12.5-25 mcg 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 mcg/day with increases of 25 mcg/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 mcg/kg/day.

Pediatric Dosage (Newborns): The recommended starting dose is 10-15 mcg/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 mcg/day of Levothyroxine Sodium.

Pediatric Dosage (Infants and Children): In children with chronic or severe hypothyroidism, initial dose of 25 mcg/day with increments of 25 mcg 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 mcg/kg/day
• 3-6 months: 8-10 mcg/kg/day
• 6-12 months: 6-8 mcg/kg/day
• 1-5 years: 5-6 mcg/kg/day
• 6-12 years: 4-5 mcg/kg/day
• >12 years but growth and puberty incomplete: 2-3 mcg/kg/day
• Growth and puberty complete: 1.7 mcg/kg/day.

The dose should be adjusted based on clinical response and laboratory parameters.