#415 ‒ AMA #91: Understanding lab testing: what blood work can and cannot tell you about your health and disease risk

Hey everyone, welcome to a sneak peek, ask me anything or AMA episode of the drive podcast. I'm your host, Peter Attia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created, or you can learn more now by going to peterattiamd.com forward slash subscribe. So without further delay, here's today's sneak peek of the ask me anything episode. Welcome to ask me anything AMA episode 91. Today, we're going to talk about lab testing. Labs are often the first thing people reach for when they want an answer to probably the most important question imaginable, which is, am I healthy? They're objective, numerical, and come with reference ranges. So it's easy to treat them as a report card on your entire health status. But that instinct kind of oversells what labs can actually do. Their real utility is actually a lot more nuanced than that. So today we're going to walk through where lab testing is genuinely helpful, where it's useful but incomplete, and where it tells us very little or frankly, nothing. And it gives you a framework for noticing the difference. So we're going to cover the first thing we're going to talk about, and then we're going to cover why people turn to labs to answer the am I healthy question, and what that question really means in the context of longevity, how to use blood work for each of the major chronic disease states, cardiovascular disease, metabolic dysfunction, cancer, and neurodegeneration, and what labs are missing in each case, what labs can and can't reveal about the organ systems in our body, and why more tests doesn't necessarily mean more useful information, why large direct-to-consumer panels and biological age scores can look sophisticated without necessarily changing a single clinical decision, how the picture changes when we shift from lifespan to healthspan, and why physical function, cognitive function, and emotional health mostly can't be captured in a blood draw. And we'll provide you with a practical set of questions to ask about any lab test, so you'll know what it's actually telling you, and perhaps more importantly, what it isn't. If you're a subscriber and you want to watch the full video of this podcast, you can find it on the show notes page, and if you're not a subscriber, you can watch the sneak peek of this video on our YouTube page. So without further delay, I hope you enjoy AMA number 91. Peter, welcome to another AMA. How are you doing? Very well, thanks. Awesome. So today's AMA, we're going to focus on lab testing, and if you compile all the questions people send us, the vast majority of them will touch this topic at some level, meaning someone says, hey, I just got blood work done, and the result of X was Y. What should I do? So I think it's not only a topic that is interesting that a lot of people care about, but it also seems like this is where people really focus on, you know, a report card of their health in a way. And so I think what would be helpful is when we start is for you, when you work with patients, you're obviously reviewing labs with them often, and when you do it for the first time, you know, what do you hear from them? What do you hear that patients, typically, are hoping that these labs will tell them when you're going through that review? Well, I mean, I think people rarely say explicitly, hey, I just want to know if I'm healthy or not. I mean, I think more broadly, there's a belief, and over the years, in anticipation of that, I've sort of preemptively addressed this on every first lab call. But the belief is that, hey, by the time we're done this exercise today, I'm going to know everything I need to know about my health. And obviously, you know, a subset of that, or at least subservient to that question, is I will know if I'm healthy, right? And again, it's a very understandable assumption to come in to a lab assessment with, because for the most part, when you've interacted with the healthcare system, the only routine maintenance things that tend to get done are lab testing. Now, of course, there's more than that, but we tend to think of imaging in a separate category. Obviously, a woman who gets her mammogram every year would also consider that a part of her routine health maintenance. But for most people, when we interact with our doctors, we're doing so around lab tests. And again, they're objective, they're numerical, they have these reference ranges. I mean, all of these things about them make them feel like they should be complete. And I think there's another thing, which is that if you don't fall outside of a reference range, and therefore nothing is going to happen, you're not going to be able to do anything. And so I think that's a getting flagged, I think people sort of assume, hey, all systems are go. You know, the check engine light isn't coming on, so everything is okay. And I would say that that view has probably been amplified over the past few years because there is really no shortage of direct-to-consumer testing products out there. And that's kind of, I think, doubled down on that belief system, which is, hey, this is the thing you need to know. And if you buy our D2C product that will check your labs and, frankly, even test lots of labs, we're going to have the solution to every problem. And so I usually just start by explaining where I think the labs are valuable, but also where their blind spots are. And I think that's an important discussion to have, so that at the end of the lab discussion, I usually end up saying something to the effect of, look, we will know roughly a third of what we care to know about you. Maybe a bit, maybe 25%. And that's a very important 25%, but we have a lot of work to do to really kind of get under the hood of truly understanding risk across everything that we care about. And that's something we're going to dive into much more detail here today as AMA. But I think what may be helpful is kind of stepping back, you ask the question, you know, are you healthy, right? And that's ultimately what people care about and want to know. And so when you're trying to understand the answer to that question for your patients, you know, how do you go about that? What are you, what are you looking at? And what are you truly trying to understand around that core question of, am I healthy? I mean, look, I think you have to start with defining what that means. And I think there are different ways to define that. If you're talking to a patient who has just finished chemotherapy for cancer, then the definition really probably should center around that, right? It should be, am I NED? NED means no evidence of disease. So has the chemotherapy worked? Is the cancer for all intents and purposes gone? Are my blood counts back to normal? Because chemotherapy often wreaks havoc on the hematopoietic system. And that frankly might be all you care about, right? Am I not anemic? Have my white cells come back? And am I free of cancer? And that would constitute the definition of, am I healthy at the moment? And so in our context, in our practice, which I actually think reflects what many people are hoping to achieve when they, when they think through this question, we are really trying to think about it through the lens of what are the threats to longevity. And again, longevity has this very, at least in our view, pretty clear definition. That's, that's pretty straightforward, right? Which is it's the, it's the product of both lifespan and healthspan. And therefore, if you're, if you're in pursuit of better longevity, what that's saying is I want to live longer. And I want to live longer. Or I want to live as long as possible in as high a state of health as possible. And, and not having one of those things is insufficient. So living a long time in poor health, that's, that's not optimal. And having a short life in high health is also not optimal. So we, we want both of those things and we frame it through the lens of what are the impediments to those things. And it's really, really important to think about the impediments, the things that will shorten your life. So the, that is cardiovascular disease, cancer, neurodegenerative and dementing diseases, metabolic disease, accidental deaths. Those are really the big ones. Now, of course, there are also organ specific diseases and things like that, that can fit in there. And we would always address those when relevant. So, you know, a person can also die from chronic obstructive pulmonary disease. If they have a longstanding history of smoking, kidney disease, liver disease, that is unrelated to metabolic disease, et cetera. So, so there are other things in there, but you're capturing most of it through what we just described. And then on the health span side of things, we're really talking about physical health. And so that's, you know, freedom from pain, strength, endurance, excellent mobility, basically the ability to do anything you want physically. And different people will have a different threshold, of course. So some people will have very high aspirations. And some people will have very high aspirations. And some people will have very modest aspirations. And others will have modest aspirations. And therefore, they'll have a different standard for what constitutes healthy. Then there's a cognitive component to that, which is the ability to, to engage with your, with your brain, right? So this is everything from processing speed and short-term memory and long-term memory, executive function, all of those things. And then there's an emotional component, which is again, made up of many things, but it includes sense of purpose, happiness, strength of relationships, emotional resilience, high distressed, tolerance, all of those things. And as we go through this exercise, we feel that health constitutes everything I just talked about. And And then we talk about how does the lab result help those things? Is it informing those things? And if so, great. And if not, then do we have another way that we can look at those things? And so before we kind of dive into labs as it relates to each of those kind of major diseases and categories you laid out, I think from a high level, how do you think about like a single snapshot of someone's lab? So if you're meeting with a patient for the first time and you have their labs from the week prior, right? How informative is that compared to if you have the labs from a week prior, as well as like a longer history of all the random times that they went to the doctor? Well, I think there are a couple of things embedded within that. The first is reliability of a lab. So if you only have a snapshot, if I only saw your labs, Nick, from today or last week, and I had no access to anything else, it would be really difficult to make a decision, even in the context of something that was abnormal, because I truly don't know if it is abnormal or if it's just actually a laboratory error. So you always have to have that in the back of your mind. And that's much easier to evaluate when you have longitudinal data. Furthermore, even if I know that it is a barrier, pardon me, not a barrier, but it is a barrier, I don't know if it's a barrier. I don't know if it's a barrier. If I know that, hey, that result is actually what it says it is, I don't necessarily know how long it's been abnormal. And in some cases that might matter. So I'll give you an example. If I see that your C-reactive protein is three, and if this is a highly sensitive C-reactive protein, that would be quite elevated. And then let's assume I just immediately repeated the test and lo and behold, it was three, not a lab error. Okay. But is it just three this week? I mean, maybe you're sick. Maybe you were vaccinated two weeks ago, and this is still some lingering level and it's coming back down, but it was 42 weeks ago. But your baseline is 0.5. I can't figure out if this is sort of chronic inflammation or if it's reactive, if it's going up, if it's going down. So it would be difficult for me to sort of weigh in and say that we're going to implement this playbook that we typically implement for people that have high inflammation. The same, I think, would be true for something like ApoB or LDL cholesterol. So if your LDL cholesterol is, let's say it's 160 milligrams per deciliter, that's, that's, that's very, very high, right? That would put you above the 80th percentile. If that's just that high, because you've gone on a diet in the past, you know, three months that has you mainlining saturated fat and your ApoB and LDL-C have gone up, you know, that's kind of a different situation than if it's been that high your whole life, which might have a genetic condition that's driving that. So I think longitudinal data are valuable, but you also have to work with what you have. There are some people who come in with very little longitudinal data and you, you know, you still have to make decisions based on the information you have. Obviously there are certain things that you don't need to check more than once, LP little a, ApoE or any other genetic test, assuming that the answer you got is correct and the lab was, was done. So I don't know, hopefully that answers your question that, that it's a bit of both. No, for sure. And I think it will be helpful now to kind of go through the major chronic diseases one by one that you laid out earlier and just talk about, okay, where are labs helpful and where do they kind of leave a picture still unpainted? So let's start with the biggest killer cardiovascular disease. So what do labs tell us and how helpful are they in understanding someone's risk of this disease? Thank you for listening to today's sneak peek AMA episode of the AMA podcast. If you're interested in hearing the complete version of this AMA, you'll want to become a premium member. It's extremely important to me to provide all of this content without relying on paid ads to do this. Our work is made entirely possible by our members. And in return, we offer exclusive member only content and benefits above and beyond what is available for free. 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