Latest research on Levothyroxine

The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (monoiodotyrosine) and the coupling of iodotyrosines (diiodotyrosine) in the thyroglobulin. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine which exerts a broad spectrum of stimulatory effects on cell metabolism. [PubChem]

Levothyroxine dosage

Because about 70% of an orally administered dose of T4 is absorbed, individuals unable to ingest L-T4 should initially receive 70% or less of their usual oral those when the medication is given intravenously. [source, 2016]
One possible rare cause of inability to achieve a suppressed TSH despite high doses of L-T4 is Thyroid hormone resistance, also referred to as impaired sensitivity to Thyroid hormone. [source, 2016]
Lifelong treatment of Levothyroxine replacement was required at a dose of 100–200 μg per day, depending on weight and sex, and serum TSH was followed up to adjust the dose of Levothyroxine. [source, 2016]
She started taking hormone replacement therapy (Desmopressin acetate 50 μg twice a day, Prednisolone 7.5 mg a day, in divided doses every morning and afternoon, and Levothyroxine 75 μg a day). [source, 2016]
This provides an explanation as to why Levothyroxine is prescribed in doses that suppress TSH, that is, in order to prevent the growth of micro-metastases and/or remnant Thyroid tissue following conventional therapy for Thyroid cancer. [source, 2016]
However, statistically significant decreases may be obtained by increasing the dose of Levothyroxine used in treatment, which is expected to further decrease TSH values and by prolonging the treatment duration. [source, 2015]
The dose of L-T4 is regulated based on TSH level, which should remain in lower limit of normal range. [source, 2015]
Thyroid function was assessed, and in the case of insufficient replacement therapy, the dose of L-Thyroxine was adjusted. [source, 2015]
Because subclinical hypothyroidism (elevated TSH and normal fT4 levels) was observed, the initial Levothyroxine dose was set at the conventional total daily dose, which can be as low as 0.05 mg; this resulted in improvement in the mass lesion and thyroid function tests. [source, 2015]
The range of the dose of Levothyroxine applied in our patients was very wide (0.32–1.59 μg/kg/day). [source, 2015]