Thyroid Conditions

Levothyroxine Not Working? Here's What Science Says About Adding T3 A patient-friendly guide to combination therapy, desiccated thyroid extract and pregnancy Evidence reviewed: September 2026 Most people with hypothyroidism are treated with levothyroxine, a synthetic form of the thyroid hormone thyroxine (T4). The body normally converts T4 into the more active hormone triiodothyronine (T3). For most people, that arrangement works well. Some, however, continue to experience ti