How should levothyroxine dosage be adjusted after diagnosing hypothyroidism?

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The main idea is that managing hypothyroidism with levothyroxine relies on the TSH level to guide dosing. After starting therapy or changing the dose, TSH should be checked about 6–8 weeks later because that interval lets the hormone reach steady state and allows the pituitary to reflect the new thyroid status. The goal is to bring TSH into the reference range for the patient, adjusting the dose up or down based on that result. Relying on Free T4 alone doesn’t provide the full picture of thyroid status for routine dose adjustments, since TSH is the sensitive indicator of overall hormone activity in most patients. Dosing by weight alone or checking randomly every few months would miss the individual variability and the time needed to achieve a stable state. After achieving a normal TSH, monitoring is typically spaced out, with more frequent checks if symptoms change or in special situations like pregnancy or changes in comorbidity.