Tuesday, June 11, 2013

Armour Thyroid Reconsidered



 
Armour Thyroid Reconsidered


Most endocrinologists prescribe brand name levothyroxine (T4) for their patients with underactive thyroid. An underactive thyroid is also known as hypothyroidism.

Levoxyl is a low cost brand which unfortunately is not now available because of some production problems. Other brands of T4 are Tirosint and Synthroid
Both of these brands are lower cost than generic T4 but generic T4 may be less reliable.

We generally frown upon the addition of T3 along with T4. 
Doctors who prescribe both do so go most evidence that shows no benefit in clinical trials.

Recall from my previous post that your body makes the T3 it needs when you give sufficient T4. Some researchershave suggested that some patients may have a reduced ability to convert T4 to T3  and this may affect their response to T4 treatment.

Armour Thyroid is a form of dessicated thyroid extract derived from the thyroid glands of pigs. As an extract it contains both T3 and T4. The chemical structure of the T4 in the Armour Thyroid is the same as that found in Synthroid.

Armour Thyroid is no more or less “natural” than Synthroid. And you know by now from my previous posts just how meaningless is the term “natural”.

The interesting news is that the first rigorous clinical trial comparing Armour Thyroid to Synthroid has just been published!

In this study the researchers gave 70 adults with hypothyroidism either Armour Thyroid or Synthroid for 16 weeks and then switched to the other treatment. That means that each patient was treated with each preparation. Patients and the doctors did not know what pill they were taking since each pill was in an identical appearing capsule. This study was a double blind randomized crossover trial.

After 6 weeks they adjusted the dose by measuring the TSH in the morning. One milligram of Armour Thyroid appeared to be roughly equivalent to 1.47 micrograms of levothyroxine. It is likely to be very important when that TSH is measured especially in those on thyroid extract which contains T3. In this study, the lab draw was done before the Armour Thyroid was taken that morning.

During treatment with the Armour Thyroid patients lost on average 2.8 pounds. And 49% of patients preferred Armour Thyroid whereas 19% preferred Synthroid and 33% had no preference.

Overall there was no difference in symptoms or in neuropsychological testing.

I think this trial, although fairly small,  is important and should make doctors reconsider the use of Armour Thyroid in selected patients. This study has already changed my practice.

 I look forward to seeing these results confirmed in another larger study. 

Daniel Weiss MD CDE FACP PNS CPI




           

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