How Effective Is Levothyroxine for Hypothyroidism?

Levothyroxine is a synthetic replacement for the hormone thyroxine (T4), which is normally manufactured by the thyroid gland. It is often taken by patients whose thyroids do not secrete the hormone properly. Treatment with this drug has been shown to significantly reduce symptoms in some patients. It also may prevent the slowdown of some body functions when associated with certain medical conditions. Like any drug, people taking levothyroxine for hypothyroidism should be aware of potential side effects and interactions with other medications they may be taking.

Hypothyroidism occurs when the thyroid gland stops making the T4 hormone. The thyroid gland is located in the neck at the base of the throat, in a butterfly shape on either side of the trachea. It is controlled by the pituitary gland, deep in the brain. This gland is responsible for the production of thyroxine (T4) and triiodothyronine (T3), which help to regulate the body’s basal metabolic rate (BMR) and its calcium regulation. Symptoms of hypothyroidism include fatigue, sensitivity to cold, weight gain, dry skin and hair and cognitive changes.

Thyroid disease is diagnosed primarily through blood tests and an examination, to determine the best dosage of levothyroxine for hypothyroidism for each individual patient. Too little of the hormone will not relieve symptoms, and too much can cause hyperthyroidism, so a proper balance is essential. Patients who are undiagnosed or who don’t use the medication can eventually fall into myxedema, or severe hypothyroidism. Body and brain functions will slow until they shut down, resulting in coma or death.

Levothyroxine for hypothyroidism should ideally be taken at the same time every day, and may be taken with or without food. It is recommended the patient use the same brand, since generics can vary their ingredients and some may be sensitive to changes. Some other drugs can interfere with the absorption of levothyroxine by the intestines or cause the body to metabolize it too quickly, resulting in periods of lower levels. The patient’s physician and pharmacist should both remain aware of any other medications being used.

Pregnant women who need levothyroxine for hypothyroidism are not usually advised to stop taking it. It is considered relatively safe to use during pregnancy, and a higher dose may be needed to ensure the fetus gets enough hormone. A deficiency in infants can cause severe mental retardation. Hypothyroidism requires lifelong therapy and regular monitoring with yearly blood tests, or more often if symptoms recur or the patient’s needs change.