Levothyroxine

Levothyroxine is a thyroid medicine used as hormone replacement therapy for those diagnosed with hypothyroidism (underactive thyroid gland). The most common cause of hypothyroidism is Hashimoto's thyroiditis.

The thyroid gland is responsible for producing thyroxine (T4). If the thyroid is not producing enough T4, then the synthetic hormone Levothyroxine is taken to replace the missing hormone.

Theory
The addition of synthetic thyroid hormone compensates for an underactive thyroid gland. This can control hypothyroid symptoms like low energy, but is not a cure.

Evidence
Levothyroxine has been around for many years treating patients with an underactive thyroid. It has substantially improved the lives of millions of hypothyroid patients since its introduction in 1949.

Lingering symptoms
Levothyroxine is prescribed to treat hypothyroidism (low thyroid hormone). Physicians often adjust dosage in an effort to normalize thyroid-stimulating hormone (TSH) levels. However, many patients report no change in symptoms, even after thyroid medication has lowered their TSH to normal levels.