What is the recommended timing for checking TSH levels after initiating therapy for hypothyroidism?

The recommended timing for checking TSH (Thyroid-Stimulating Hormone) levels after initiating therapy for hypothyroidism is typically around 6 weeks. This duration allows sufficient time for the medication to achieve stable serum thyroid hormone levels and for the body to respond adequately to the treatment.

After starting thyroid hormone replacement therapy, it generally takes about 4 to 6 weeks for the TSH levels to reflect the physiological changes brought about by the medication. Checking too early, such as at 1 week or even 4 weeks, might not provide an accurate assessment of the therapy's effect since TSH may still be adjusting. While monitoring at 12 weeks could be appropriate for subsequent evaluations, following the initial therapy initiation, waiting 6 weeks ensures a more accurate and stable measurement of TSH, allowing for proper adjustment of therapy if necessary. This timing strategy is critical to achieving optimal management of hypothyroidism.