Thyroid Replacement

Thyroid replacement therapy is a provider-guided treatment for people whose thyroid gland does not produce enough thyroid hormone (hypothyroidism). It supplies the hormone the thyroid cannot produce in adequate amounts, with the goal of restoring thyroid function to the appropriate range.

Levothyroxine is synthetic T4 and is the preferred treatment for most patients. The body converts T4 into active T3 as needed. Liothyronine is synthetic T3, acts more quickly, and may be considered for select patients, usually as an addition to Levothyroxine, after careful evaluation.

No. Levothyroxine and Liothyronine are commercially manufactured prescription medications. They are not compounded.

Yes. A TSH and free T4 are typically reviewed before treatment, and additional tests may be ordered when clinically appropriate. For most adults taking Levothyroxine, TSH is rechecked about 6 to 8 weeks after starting or changing the dose, and every 6 to 12 months once the dose is stable. Symptoms alone cannot determine whether the dose is appropriate.

Take it exactly as prescribed, at the same time and under the same conditions each day. Levothyroxine is commonly taken once daily on an empty stomach, 30 to 60 minutes before breakfast, with water. Calcium, iron, antacids, and certain other medications or supplements can reduce absorption. Your clinician or pharmacist will advise how far apart to take them.

No. Thyroid hormone must not be used to treat obesity or for weight loss. Excess dosing can cause serious or life-threatening toxicity.

When the dose is appropriate, thyroid replacement is generally well tolerated. Most side effects reflect a dose that is too high, such as a fast or irregular heartbeat, nervousness, tremor, difficulty sleeping, heat intolerance, sweating, diarrhea, or unintended weight loss. Seek urgent medical attention for chest pain, severe shortness of breath, fainting, a new sustained rapid or irregular heartbeat, or signs of a serious allergic reaction.

Tell your clinician about heart disease, arrhythmias, high blood pressure, adrenal or pituitary disorders, diabetes, osteoporosis, pregnancy, and all medications and supplements. Also tell them if your medication’s manufacturer or formulation changes. Pregnancy requires prompt notification because thyroid hormone needs may change early in pregnancy.

Thyroid replacement is not an instant stimulant. Levothyroxine may take about 4 to 6 weeks to reach its full effect at a given dose, and follow-up labs are reviewed at about 6 to 8 weeks. Many patients need lifelong treatment with periodic lab testing and follow-up.