Benefits of Desiccated Thyroid Vs. Synthetic Thyroid Therapy

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Fatigue, weight gain, depression, constipation, and dry skin are all signs of slow metabolism related to a poorly functioning thyroid. Hypothyroidism is a common endocrine disease that can be due to an underlying attack by the immune system, a lack of nutrients, miscommunications between other hormones like cortisol, and of course surgery or treatment to remove the thyroid. While the causes of hypothyroidism may be different in each individual, one of the most common treatments prescribed no matter what the cause is due to is thyroid medication.  

There are two main classes of thyroid medications, synthetic and desiccated thyroid. From clinical experience, the medication I see most often prescribed is synthetic T4 medication like Synthroid or it’s generic version, levothyroxine. Sometimes I’ll see synthetic T3 added but it is rare.  What I don’t see very often prescribed is desiccated thyroid medication which I find unfortunate.  

There are 4 main thyroid hormones, T1, T2, T3, and T4. Synthetic T4 medication supplies the body with exogenous T4 that theoretically should convert into T3 in the body. T4 has a longer half-life than T3 so it is released slowly over time after taking thyroid medication. When doctors order labs to check how the thyroid medication is working, they will often order a TSH and Free or Total T4. These labs often times come back looking normal, so the doctor doesn’t change the medication even if the patient is still feeling symptomatic.  But many people don’t effectively convert T4 to T3 in the bloodstream and thus the thyroid hormones don’t actually enter the cells to increase metabolism and help with the symptoms of hypothyroidism. 

On the other hand, desiccated thyroid hormones are derived from porcine thyroid and molecularly resemble human thyroid hormones T1, T2, T3, and T4. What I love most about desiccated thyroid hormones is that they contain T3. T3, while shorter acting than T4, is actually the biologically active thyroid hormone which means it’s the thyroid hormone that enters cells from the bloodstream and increases metabolism.  Time and again, I will test patient’s free and total T3 levels (who have been diagnosed with hypothyroidism and who are taking a T4 only thyroid medication) and find their T3 levels to be low even though their TSH and T4 levels look ok. By supplying the body with a mixture of both T4 and T3 thyroid hormones, desiccated thyroid medications provide the body with both long acting and short acting forms and from clinical experience work a lot better in resolving symptoms of hypothyroidism.

There a variety of brands of desiccated thyroid hormones including Armour Thyroid, Nature-Throid, WP-Thyroid, and NP-Thyroid. They are all similar in their main ingredients, but each contains different fillers and so one medication may be better than another for certain sensitive individuals. 

It’s also important to note that desiccated thyroid hormones may not be appropriate for all individuals including those with irregular heartbeats or atrial fibrillation. 

In summary, it’s important to get the right labs tested including free, total and reverse T3 levels and consider desiccated thyroid hormones if you are still feeling symptomatic despite taking a T4 only thyroid medication.