From a front lines clinical perspective, what does the treatment roadmap for combination T3/T4 therapy look like? What approach to combination therapy do you recommend for the primary care, internal medicine, and/or women’s health specialist?
So when we decide to place a patient on combination therapy. Uh, we, we have, uh, a couple of options. We have, uh, just prescribing that patient Cytomel and levothyroxine, Cytomel being the sodium T3 that's, uh, uh, sold, or, Uh, a lot of physicians put, uh, place patients on dissiccated thyroid extract with DTE that has, uh, multiple different brands. So DTE, as I mentioned before, historically it was the first form of treatment of hypothyroidism and that it has, it, it was used for, uh, 90, 100 years before it was, uh, almost replaced by levothyroxine. DTE is just thyroid extract from pigs. Uh, it, it used to be that it could be done from different animals. Uh, however, Uh, today in the United States, all DTE is produced based on thyroid that has been removed from pigs, from slaughterhouses. So, uh, Chicago was the birthplace of DTE, uh, here with the. Uh, with the slaughterhouse armor and swift, they had so many thyroid glands because they were killing all those, uh, animals that they developed this, uh, armored thyroid, for example, it comes from the armored slaughterhouse. Uh, so DTE contains T4 and T3. If it's from pig, it's in a ratio of 4 to 1. So there are 4 molecules of T4 and 1 molecule of T3. DTE pills are measured in grains. Uh, it's an old way of measuring this, but it's equivalent to 65 mg. So one grain is equivalent to 65 mg of extract. In 65 mg of the extract, you will have 38 mcg of of T4 and 9 mcg of T3. And all of them should have those numbers because that's established by the United States pharmacopeia. So, uh, to produce DTE, uh, uh, laboratory needs to follow those standards from the United States pharmacopeia which says 39 mcg of 38 mcg of of thyroxine and 9 mcg of T3. Uh, they allow you to have about plus minus 10%, so there's a small range, uh, around the 38 and a small range about the 9 mcg, but that's sort of standard. Now, Uh, if you start a patient on levothyroxine, as I mentioned, you would give about 1.5 mcg of levothyroxine per day, per kilo. For DTE, uh, I actually looked at several studies and it seems that the dose that will provide replacement, uh, for a hypothyroid patient, Is between one grain and two grains, about 100 and 20 mgs of DTE per day. But again, this is just like levothyroxine. It depends on the absorption rate, the efficiency, And it, again, depends on TSH. So, how are you going to monitor that? First, you should start with a small dose. You should never go and give a full blast of DTE because it does contain T3 and you want to, Avoid that. Remember, levothyroxine is very safe because it does not contain T3. DTE does contain T3. So, I would start with half or even less of half of DTE, yeah, of the dose. And then build your way up. Now, it, what should you be measuring? You should be measuring TSH, Free T4 and T3. Why you measure T3? Because you're giving T3. You wanna know what's, what are you doing to the T3 levels of that patient. If you were not giving T3, uh, it wouldn't be helpful, but you are giving T3. So when do you measure this? Uh, because T3 has the issue of a rapid absorption and a rapid half-life, you need to measure. Fasting before the patient takes the pill so you know how much T3 is coming from the previous pill that that patient received and 3 hours after the patient took the pill because then you know how high that T3 in the circulation is going. Let's say you have a baseline of a T3 that's about 120 nanograms per dL within well within the normal range. But after 3 hours that the patient took the pill, T3 levels are going to 250. That's too high. It means that during a significant number of hours, that patient is going to exhibit thyrotoxic levels of T3, and you don't want to have that. Therefore, I always like to measure baseline and the peak at around 3 hours because then you you can tell yourself I'm, I'm happy I'm safe here because even though the before and after they took the pill that the excursion of the T3 levels did not go outside of the normal range. In fact Francesco Celli did some studies in his lab in which he measured the fluctuation of T3 in the circulation after patients took different amounts of T3, and he saw that if a patient takes uh. Between 2.5 and 7.5 mcg of T3. Uh, twice a day that patient, the excursion of T3 levels are, it's not going to be outside of the normal range. Above 7.5, it might take that patient to above the normal range. Now the issue is that one grain of DTE contains 9 mcg of T3, which is slightly more than the 7.5 mcg that Francesco, uh, determined. So, I would be careful. I would be monitoring that because we want to make sure that we're not going overboard and the patient is not experiencing a few hours of thyroid toxicosis or elevated serum T3 after they took that pill.
