Bioidentical Thyroid Hormone

Support for the use of Armour Thyroid or Naturethroid

When to Prescribe Thyroid Hormone Combo? Dr. Michael T. McDermott, a professor of medicine and clinical pharmacology, and director of endocrinology and diabetes practice at the University of Colorado Hospital, Aurora gave his expert opinion at an update on internal medicine sponsored by University of Colorado: “Adding T3 or liothyronine is a reasonable treatment strategy when symptoms of hypothyroidism persist on optimal levothyroxine or T4 alone.”  However, he said it should belong on the bottom of the management plan for the difficult thyroid patient only after coexisting autoimmune disease (like Hashimoto’s, rheumatoid arthritis, vitiligo, systemic lupus erythematosus and Addison’s disease) and other medical illnesses are ruled out.

Five published studies demonstrate that many patients experience lingering fatigue, memory problems, and other symptoms despite while on T4 and while their TSH (thyroid stimulating hormone) is in the target range of .5-2.0 mU/L.

He often measures a vitamin D level in his difficult cases of hypothyroidism because vitamin D deficiency is a common cause of fatigue.  He also encourages his difficult patients to eat a well balanced diet and get regular exercise.  He also refers them for treatment of depression. Only after doing all of the above does he add T3.

LT4/LT3 therapy is controversial.  The first ever randomized clinical trial was positive (N.England J.Med. 1999;340:424-9), meaning patients did better on it than LT4 alone, however, may studies that followed after showed no benefit.  So the book was closed, and doctors were not prescribing the combination therapy.

But a recent study demonstrated that patients who had a certain genetic polymorphism (16%) had impaired conversion of T4 to T3, and significantly benefitted from the combination therapy.  (J. Clin. Endocrinol. Metab. 2009;94:1623-9).  His explanation for the previous studies failing to show benefit with combination therapy is that if about 16% have the genetic polymorphism, than the number of patients studied was not enough to detect enough patients that would benefit.

The combination he uses is 10-14:1 ratio of LT4:LT3.  He has his patients take the LT3 twice daily before 6pm on the second dose to avoid sleep issues.

He even switches to another brand of LT4 if all other options have failed since some forms of LT4 have dyes and fillers to which the patient can react to.  Tirosint is a form of Levothyroxine sodium LT4 FDA approved that has no fillers or dyes.

My Opinion: I use Bioidentical Hormone Combo First

I prescribe a lot of armor or nature-thyroid to my patients because it is bioidentical and has the combination of T4 and T3.  To be clear, not only do I use the combo described above, in the first place, but the combo is the bioidentical form T3/T4 and not the synthetic LT3 and LT4.   Most of my patients, but not all, feel much better on this bioidentical combination, and that would be more than 16% of them.  There are some patients that do not tolerate the natural thyroid hormone and thus require a compounded form of LT4/LT3.  Hence, I  will prescribe this for them in a 12:1 ratio which is precisely what Dr. McDermott does.  In addition, I check most of my patients for Hashimoto’s, celiac, and vitamin D.  I also identify a lot of low thyroid in patients whose blood work does not suggest they have it, but all of their clinical symptoms do.  Once I prescribe them thyroid hormone, most of them feel so much better.  It is one of my most successful therapies for adult patients.

In conclusion, I do not put the use of combination T4/T3 therapy low on my list, rather it is the highest with major benefit to my patients.  Patients who continue to feel tired despite adequate thyroid hormone therapy then need to have their other hormones checked like adrenal function, growth hormone, aldosterone, and sex hormones.  They should also consider complete nutritional panels as well as testing for toxins and parasites like candida.  You may consider this approach as a Functional Medicine or Integrative Medicine approach.

 

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Karima Hirani, MD MPH
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