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Pharmacy and Medications

Replacement Therapy for Thyroid Disease




I am not sure which BBS you've visited. It's important to realize that information provided on the internet is often unreliable or frankly wrong.  Furthermore, it is often difficult to resolve conflicting information without medical training or access to medical textbooks. Physicians, nurses, pharmacists and other allied health professionals are interested primarily in helping sick people get better with treatment based on the best available current evidence. 

Current therapy and current best medical practices reflect modern medical science and our current understanding of diseases and their treatment.  As we make more discoveries, treatment may change.  People with differing views are welcome, but should be held to the same scientific standards as those applied to current therapy. I would dismiss conspiracy theories in which doctors are in cahoots with drug companies to harm patients as total nonsense.

Armour Thyroid (desiccated porcine (pig) thyroid gland) was the only treatment for hypothyroidism for about 50 years, but it was found that the amounts of T3 and T4 varied greatly from batch to batch.  The product has been reformulated to address the batch to batch inconsistencies, but it does not provide better treatment of hypothyroidism than T4 alone.  I would not recommend starting new patients on this medicine.   However, it is probably appropriate to have patients who are well controlled on this product to continue using it.  

Thyroid products sold as dietary supplements on the internet contain desiccated thyroid from various animals. These products are likely to contain inconsistent amounts of thyroid hormones. We cannot recommend using these products, because they are likely to produce inconsistent results.   

Synthroid is one of several brands of levothyroxine. Levothyroxine, also called T4, acts exactly the same as one of the naturally occurring thyroid hormones. The other thyroid hormone is liothyronine or T3. When the thyroid is working normally, it produces T4 and the body maintains a constant ratio of T4 to T3.  Levothyroxine alone is the most commonly used hormone for thyroid replacement therapy because it causes less side effects, it is easier to use, and exactly mimics the action of the levothyroxine our bodies produce.    

Levothyroxine does not "cure" hypothyroidism, nor does it make patients who take it to become hypothyroid. It is used after the thyroid gland has developed some type of deficiency. Sometimes doctors need to damage the thyroid gland on purpose, for example when the thyroid is making too much thyroid hormone or in the case of thyroid cancer. Levothyroxine replaces thyroid hormone in patients who are unable to make their own due to disease or other damage to the thyroid gland.  The correct dose will prevent the medical problems that occur when a person does not make enough of their own levothyroxine. 

Patients who need levothyroxine almost always need to take it for the rest of their lives. This is because the hormone is needed for normal body functioning and the body cannot make its own. In this sense is works like insulin does in patients with insulin dependent diabetes to replace the insulin that the patient's pancreas is unable to make.

Your doctor is in the best position to determine the most appropriate medicine for you, but by all means you are welcome to talk to someone for a second opinion.  Your doctor or a pharmacist who knows you can help provide medically sound information based on current therapeutic practice.

This response was prepared in part by Eric Gillespie, a PharmD student at the University of Cincinnati College of Pharmacy.

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Response by:

Robert James Goetz, PharmD, DABAT
Assistant Professor of Pharmacy Practice
College of Medicine
University of Cincinnati