What Is T4 Replacement in Thyroid Disease?

T4 hormone replacement is often used in the treatment of hypothyroidism, or under-active thyroid. In this case, your thyroid gland does not produce enough of this type of hormone. Your metabolic rate decreases as a result, which affects certain body functions.

Facts

• T4 is technically referred to as thyroxine or tetraiodothyronine. It interacts with another hormone produced by the thyroid, called T3, or triiodothyronine. According to endocrineweb.com, T4 hormones are not as abundant in your body, and if they lack iodine atoms, they are converted to T3 hormones.

Function

• T4 hormone replacement is meant to make up for the lack of T4 hormones in your body. Without T4 hormones, your decreased metabolic rate can cause changes in your thinking processes, heart beat, body heat and energy levels.

Testing

• T4 hormone replacement prescriptions, such as Synthroid, are available in different dosages, depending on how much T4 your thyroid needs. Your doctor will administer an initial blood test to determine the correct dosage. Additional tests are conducted in the future to make sure your dosage does not need to be adjusted.

Indications

• When you are prescribed T4 hormone replacements, you must take one pill every day. Generally, it is best to take them in the morning at least 30 minutes before breakfast, because they work better on an empty stomach.

Interactions

• According to familypracticenotebook.com, T4 hormone replacement pills can interact with oral contraceptives, calcium supplements, estrogen replacement, lithium and pills containing iodine. Take such medications at least four hours apart.