Hypothyroidism means your thyroid gland is not making enough thyroid hormone for your body’s needs. Most of the hormone coming out of the thyroid is thyroxine (T4) and a much smaller amount of tri-iodothyronine (T3). The vast majority of patients will do fine given just T4 since the body can convert T4 into T3 to make up for missing T3. You take enough T4 to reduce the thyroid stimulating hormone (TSH) level to normal. Changes in the level of T4 you take are checked with blood tests no more often than every 4 weeks.
The available preparations of T4 are:
- Levoxyl, a brand name for thyroxine.
- Synthroid, another brand name for thyroxine.
- Thyroxine, the generic form of the medication.
I find no difference in the effect of these medications and use them all. Once a patient starts taking one preparation, it is probably best to continue using that one, although if the TSH remains normal, it makes no difference which preparation is used.
An occasional patient, especially one in whom depression plays a large role, is given T3 (brand name Cytomel) along with T4. This seems to help the depression. The TSH should still be normal, even with Cytomel treatment.