The Peter Attia Drive - September 21, 2026


#408 ‒ AMA #89： Thyroid health： interpreting symptoms, diagnosing and treating dysfunction, and navigating the gray zone

#407 ‒ Preventing cardiovascular and Alzheimer's disease： lowering LDL early, APOE4, and promising new therapies ｜ Michael Davidson, M.D.

Episode Stats


Length

16 minutes

Words per minute

166.94

Word count

2,728

Sentence count

128

People

Hosts:
Peter Attia
Also mentioned:
Adam

Harmful content

Hate speech

5

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Transcript

Transcript generated with Whisper (turbo).
Hate speech classifications generated with facebook/roberta-hate-speech-dynabench-r4-target .
00:00:00.000 Hey everyone, welcome to a sneak peek, ask me anything or AMA episode of the drive podcast.
00:00:15.820 I'm your host, Peter Atiyah. At the end of this short episode, I'll explain how you can access
00:00:20.280 the AMA episodes in full, along with a ton of other membership benefits we've created,
00:00:24.900 Or you can learn more now by going to peteratiyamd.com forward slash subscribe.
00:00:30.600 So without further delay, here's today's sneak peek of the Ask Me Anything episode.
00:00:38.820 Welcome to Ask Me Anything AMA episode 89.
00:00:42.040 In today's AMA, we look at managing the thyroid and unusually complex hormonal system that
00:00:47.600 is, I guess, if anything, more nuanced and in some ways controversial than the management
00:00:53.820 of other hormone systems. In this episode, we discuss the basic biology of the thyroid gland
00:00:59.320 and how it's regulated by the brain and specifically the pituitary gland and hypothalamus.
00:01:04.980 And then we talk about how thyroid activity is regulated locally at the tissues where it's used.
00:01:10.860 Talk about why hypothyroidism is common but easily misdiagnosed by symptoms alone.
00:01:17.160 Talk about how hypothyroid is both underdiagnosed and overdiagnosed and why some patients on
00:01:23.700 standard thyroid hormone replacements still don't feel well. We talk about the appropriate use of
00:01:28.800 combination therapy. So that's T3 and T4, as opposed to just the standard treatments of T4.
00:01:34.920 We talk about the theoretical thyroid supporting supplements. Is there any signal in all the noise
00:01:41.260 of that stuff? And then we close with, I guess, what we would consider our framework in the clinic.
00:01:46.480 So who actually needs testing, what a reasonable lab panel might look like, and then how to think
00:01:52.340 about a patient whose labs are normal, but who still doesn't feel right and whom you might
00:01:57.260 suspect is actually deficient in their thyroid hormone. So if you're a subscriber and want to
00:02:01.800 watch the full video of this podcast, you can find it on the show notes page. And if you're
00:02:06.420 not a subscriber, you can watch a sneak peek of this video on our YouTube page. So without further
00:02:10.680 delight. I hope you enjoy AMA number 89. Peter, welcome to another AMA. How are you doing?
00:02:21.240 Very good. Thanks. Well, today we're going to talk about the thyroid. So this is something that
00:02:25.940 it seems like people hear about all the time, but really don't understand well. And so I think
00:02:31.340 what might be helpful for people before we get into it is maybe just explaining why this is such
00:02:36.000 a complex, complicated topic. Yeah. I don't, I mean, I think there's probably several ways to
00:02:41.420 think about that, but certainly one reason is that the regulation of thyroid hormones is quite
00:02:47.540 complicated and that's true for several reasons, but I'll state one at the outset, which is it's
00:02:53.660 a hormone system for which the Goldilocks principle applies, right? Too much is a problem and too
00:02:59.460 little is a problem. Now, conversely, if you think about testosterone, you know, male androgens,
00:03:05.080 that's not the case, right? There's really no naturally occurring scenario where you have too
00:03:09.540 much of it. And by the way, even when people are having testosterone replaced, if you give them
00:03:15.340 too much, they generally just feel better. So it's not, you know, it's actually a more asymmetric
00:03:20.680 problem. But the thyroid is particularly nuanced. And there's a feedback system in the brain that
00:03:25.740 works a lot like other hormones we know about, including testosterone. But again, a second thing
00:03:33.100 that then makes this really complicated is that you have an inactive hormone that is the thing
00:03:38.240 that's actually gets getting secreted by the thyroid gland that gets converted to an active
00:03:43.380 hormone locally. And by the way, there are different ways that it gets converted. So there
00:03:48.780 are different enzymes that convert it. And it's so, so, so I think that's that we're obviously
00:03:53.880 we're going to talk about all of these things. I guess the other thing I would say is how you
00:03:58.980 interpret the lab test is a little bit problematic. Again, when you are looking at something like
00:04:04.600 estrogen, progesterone, or testosterone, provided you're using the right assay,
00:04:10.320 like an LCMS test, you can very accurately measure those hormones. As we'll discuss in
00:04:16.640 the thyroid, that's not always the case. I would say another thing that makes this complicated
00:04:21.800 is the importance of how symptoms fit into the diagnosis. Now, again, that should be part and
00:04:28.120 parcel with every endocrine diagnosis. It's just that the symptoms of low estrogen and progesterone
00:04:35.140 and testosterone are much more apparent and have fewer overlaps with other potential diagnoses
00:04:42.680 than we see with thyroid. So I think when you take all of these things together, managing the
00:04:49.680 thyroid hormone is sort of a ripe environment for ideologic battles and pseudoscience and sort of 0.99
00:04:56.980 a little bit of chicanery when it comes to sometimes practitioners doing more harm than 0.98
00:05:03.220 good when they're trying to treat patients. Given that, it seems like the best place to 1.00
00:05:08.040 probably start is just explaining to people what is the thyroid and what does it actually do?
00:05:13.700 So it's a small gland with two lobes on either side of your throat, really sitting on top of
00:05:19.800 your voice box, just below the Adam's apple is really where it starts. And then it rises to the
00:05:25.000 side and then goes down the other side. So it makes a hormone, but primarily the one that it
00:05:30.180 makes is called T4. And it's called T4 because it has four iodines on it. The downstream of that
00:05:36.420 effect is that this hormone regulates the metabolic rate of basically every cell in the body. So you
00:05:41.700 can think of the thyroid gland as the gain knob on your body's metabolic amplifier. So it's not
00:05:48.360 really deciding what your cells do so much as how loudly they do it. So if you have too little
00:05:55.060 signal and everything is basically going to run cold and slow, your heart rate's going to drop,
00:06:00.300 your weight's going to probably creep up. You feel like you're operating at half capacity,
00:06:04.520 you're low in energy, et cetera. Too much of it, of course, and again, it's not a big line between
00:06:09.960 too much and too little, and everything goes up. Everything's hot and fast. So your heart rate goes
00:06:14.940 up. You might even have unexpected weight loss, anxiety, insomnia, atrial fibrillation, all sorts
00:06:20.600 of things like that. I'd say kind of roughly like 5% of adults in the United States have some
00:06:27.580 clinically meaningful thyroid dysfunction. So for that reason, I mean, it's wildly prevalent.
00:06:35.460 And that means by definition, many people listening to us right now are experiencing that.
00:06:41.300 But as I've kind of alluded to, I think it's one of the more commonly mismanaged conditions I see.
00:06:47.400 And that's obviously why I want to spend a lot of time on it.
00:06:49.300 We do see a lot of patients come into our practice who are being mismanaged in this regard.
00:06:53.900 And I think by extension, many other doctors are probably seeing that too.
00:06:58.500 Yeah. And so with that mismanagement, it's almost like there's a lot of disagreement around this, right?
00:07:02.800 It's not a super clean topic, not a super clean biology in a way.
00:07:07.220 And so why do you think that this can be such a contentious topic for doctors and people to
00:07:13.620 understand? I think because the system is complex, which is not unique to the body. But when you
00:07:21.180 combine that with the fact that we don't have visibility into its moving parts, I think that
00:07:25.540 creates a bit of a perfect storm. So as I kind of alluded to, the gland mostly secretes an inactive
00:07:31.560 pro-hormone, T4. And then there's a decision about how much of that hormone becomes the active
00:07:38.540 hormone, T3. But that decision is happening locally, tissue by tissue. Now, TSH, thyroid
00:07:46.160 stimulating hormone, is a great marker of whether the gland is being told to work harder, but it's
00:07:52.340 a step removed from what's actually happening inside the liver, the heart, the brain. Then
00:07:57.920 there's also kind of a real philosophical split. So there's a camp of physicians, I suppose,
00:08:03.240 that think hypothyroidism is underdiagnosed, undertreated. And then, you know, that's kind
00:08:10.240 of the, when you're a hammer, everything is a nail camp, right? Like any problem that anybody
00:08:14.680 shows up with, if you're depressed, if you're having GI issues, if you're, you know, having
00:08:19.480 sleep, whatever the problem is, it's hypothyroidism. At the other end of the spectrum, you have a camp
00:08:24.460 of other folks who say, no, no, no, this is completely overdiagnosed by this kind of everybody
00:08:31.120 has hypothyroidism school of thought. And basically, we're only going to treat hypothyroidism if it is
00:08:38.920 so overt that a medical school student after one hour of an endocrinology class would be able to
00:08:47.080 make this diagnosis blindfolded. As you can probably imagine, I think both of these schools
00:08:51.680 are incorrect and that there's a messy middle ground where the truth probably lies. And the
00:08:57.740 goal of this podcast, of course, is then to kind of walk people through the physiology carefully
00:09:02.660 enough that you can see both the grains of truth on each side of those schools of thought, but
00:09:09.520 perhaps more importantly, what they might be missing and therefore where we can hopefully
00:09:14.100 land on a place to treat people. Yeah. And so on that, it seems like for a lot of people,
00:09:20.020 the first time they start thinking about the thyroid is they're either tired, gain weight,
00:09:25.580 something just quote unquote doesn't feel right. You do what anyone does and they go to Google,
00:09:30.340 they search it, and there's a ton of people, a ton of things saying, hey, there's something
00:09:35.320 wrong with the thyroid, they're hypothyroid. And so how much can you actually tell from some of
00:09:41.380 those like generic symptoms like that? Yeah, unfortunately, almost nothing about,
00:09:46.600 you know, fatigue and feeling off is specific to any one organ system or cause. And we see this
00:09:53.720 in formal blinded studies trying to diagnose hypothyroidism purely off of symptom clusters
00:10:00.900 without any biochemistry. So they essentially couldn't distinguish hypothyroid from euthyroid,
00:10:06.840 meaning patients have normal levels of thyroid. The same complaints show up with sleep deprivation,
00:10:12.100 iron deficiency anemia, perimenopause, and menopause-related symptoms. And the last one,
00:10:17.640 by the way, may be one of the single biggest confounders in my practice, especially since
00:10:21.640 the timing often overlaps, but that's maybe a later issue. But what's going on inside the
00:10:26.540 endocrine system and how to fix it are actually kind of different. So you do need the rigor of
00:10:31.920 multiple data sources. And I think that a lab-first approach rather than a symptom-first approach
00:10:39.960 is more likely to get you in the high zone of probability, again, based on how nonspecific
00:10:47.200 these symptoms are. So I think it's a good place to then kind of look at it clinically in your
00:10:52.720 practice, right? So where are you seeing doctors potentially missing a real thyroid problem,
00:10:58.480 and where do you see people on the other end going too far in that other direction?
00:11:03.240 Well, look, I think a lot of medical care misses real disease when it treats a lab value in
00:11:10.400 isolation from the patient. So dismissing somebody with a patchy gland, positive antibodies,
00:11:16.060 and a family history because their TSH is, you know, quote unquote normal at 4.2.
00:11:21.420 So that's a legit failure. But just as often I'm seeing the overreach in the other direction,
00:11:27.000 and this is most visibly in this strand of what people call functional medicine that treats
00:11:33.160 subclinical hypothyroidism as close to basically a ubiquitous finding. So if you go looking,
00:11:39.680 you'll find practitioners who insist that the standard TSH ranges are too permissive
00:11:44.880 and treat a borderline free T3 or elevated reverse T3 as irrefutable proof of tissue
00:11:51.840 level hypothyroidism regardless of TSH or regardless of free T4 and sometimes regardless
00:11:57.860 of symptoms. So having decided that a patient has a thyroid problem, they will build an elaborate
00:12:04.280 root cause narrative, gut health, adrenal fatigue, toxic burden, et cetera, around kind of a lab
00:12:09.500 picture that in a large share of cases is actually within a normal variation or will normalize on
00:12:15.700 its own. So rather than just kind of accepting that a person doesn't have hypothyroidism when
00:12:19.920 their blood work comes back normal by conventional standards, they will maybe use this kind of
00:12:24.940 functional medicine framework to basically assume that there's a problem at the level of the
00:12:30.820 conversion of T4 to T3 in the tissue, ask the question, what's driving the conversion
00:12:36.740 impairment? I think in reality, a large share of patients with mildly elevated TSH will normalize
00:12:43.940 spontaneously on repeat testing. And I think over-treatment with standard thyroid hormone is
00:12:50.280 is not benign. It can actually cause cognitive symptoms, atrial fibrillation, which we've seen
00:12:54.960 countless times, bone loss, and more. So I think both failure modes are real. And some patients go
00:13:02.300 from their family doctor and get hit at one end of it and then are driven into the 0.99
00:13:08.340 clinic of a quack who hits them with the other end. And again, just to reiterate, 0.99
00:13:13.180 I think both extremes are likely doing more harm than good.
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