Here’s the problem with our healthcare system. At least in the US, it’s built around waiting. You wait until something feels wrong and you go to your doctor and they run standard labs. And if nothing’s flagged, you’re sent home and you’re told to come back next year. But what nobody tells you is by the time symptoms appear and by the time those routine labs start looking abnormal, the disease has already been building quietly for years, sometimes even decades.
And by then, organ damage has already set in. And at that point, we’re not reversing anything. We’re just managing it with chronic medications and chronic side effects and chronic disease for life. So, in this article, I want to go over four critical blood tests that I routinely order in my longevity clinic. These labs can detect problems years and sometimes decades before symptoms appear.
Now, most physicians do not routinely order these tests, so you may have to ask for these or get them on your own. But, getting these tests is only half the battle because if your doctor doesn’t routinely order them, there’s a good chance they may not be fully comfortable interpreting them, either. And the nuance matters a lot.
The same lab result or the same number can mean something completely different depending on your age or your risk factors or your other labs and your family history. So, as you read this article, pay close attention to the interpretation part of this, not just the test name. That way, you can have an informed conversation with your doctor and even push back when necessary and advocate for yourself because at the end of the day, no one has more at stake in your health than you do.
Test 1: High-Sensitivity CRP (hs-CRP)
So, let’s start with a test that can predict your risk of a heart attack years before it happens and it’s called a high-sensitivity CRP or hs-CRP. So, this test measures your level of inflammation and I talk a lot in my other videos about how inflammation drives so much of the chronic disease that we see today. Things like heart disease and strokes, cancer and even dementia.
And checking high-sensitivity CRP is a way to actually quantify that inflammatory burden. Now, you may have heard of the regular CRP test, which doctors order for infections or autoimmune flares, but that test only picks up on large and obvious spikes of inflammation. The high sensitivity CRP test is far more sensitive, and it can detect that low-grade smoldering inflammation, the kind that causes zero symptoms but has been quietly damaging your blood vessels for years.
Why Inflammation Matters for Your Heart
And here’s what makes this important. Atherosclerosis, which is that buildup of plaque inside your arteries, is just as much of an inflammatory disease as it is a cholesterol disease. So, two people can have identical LDL numbers or apoB numbers, but the one with higher chronic inflammation is at a significantly greater risk.
And the evidence for this is pretty strong. And by the way, I talk about how you should approach LDL and apoB and other important tests you need to keep track of in another video. And I’m going to post a link to that below.
The CANTOS Trial
So, here’s the study that put inflammation on the map. So, this was the CANTOS trial, where they enrolled over 10,000 patients with known heart disease, and whose LDL was relatively well controlled with a median LDL of just 82 mg per deciliter.
But, they still had high high-sensitivity CRP, so a level of two or above. So, basically, their cholesterol numbers looked fine, but inflammation was still elevated. Well, the researchers gave them a drug that specifically blocked inflammation with zero effect on LDL. And just by lowering that inflammation alone, major cardiovascular events dropped by 15%.
Now, the patients who got their high sensitivity CRP down to below two did even better. So, these folks saw a 25% reduction in major cardiovascular events and a 31% reduction in all-cause mortality, which is basically death from any cause.
And there’s a more recent collaborative analysis of over 31,000 statin-treated patients that show that patients with a high sensitivity CRP of two or above had roughly double the risk of cardiovascular death compared to those with low levels. And that was regardless of their LDL number.
And this is not to say don’t worry about your LDL because that’s still important and is still a major cause of atherosclerosis or plaque buildup, but we cannot neglect inflammation. In fact, the American College of Cardiology published a scientific statement that emphasized that high sensitivity CRP predicts your risk of heart disease just as well or even better than our standard cholesterol numbers.
What Your Number Should Be
So, with high sensitivity CRP, we want our numbers to be below one. And if it’s elevated, the goal is to find out why because it’s almost always something fixable upstream. It could be insulin resistance or excess weight or disrupted sleep or even poor dental health or emotional stress.
Test 2: Fasting Insulin
Okay, the next test I want to talk about is fasting insulin. And this lab is almost never part of a routine physical, which is a real problem. What’s typically checked is fasting glucose or hemoglobin A1C, but here’s the problem. Fasting glucose and A1C can look completely normal for years even though you’re already developing insulin resistance in the background.
Why Insulin Resistance Matters
So, why does this even matter? Well, insulin resistance is a precursor to diabetes, but you don’t develop diabetes overnight and it happens gradually. So, the way this works is insulin is a hormone that your pancreas releases after you eat. And one of its jobs is to help move glucose out of your bloodstream and into your cells where you either burn it for energy or you store it.
And the reason you get high levels of insulin as the very first sign of insulin resistance is because your body compensates before it fails. And here’s what happens. When your cells start responding less to insulin, your pancreas doesn’t just give up. It starts working overtime, and it releases more and more insulin to force that excess glucose into your cells, especially muscle cells.
And this can mask the problem for years and even a decade. Your pancreas is overproducing insulin to keep the blood sugar completely normal. So, your fasting glucose and your A1C look fine. But behind the scenes, insulin levels are climbing, and chronically high levels of insulin is not harmless.
It can drive visceral fat accumulation, and it raises your blood pressure, and it accelerates plaque formation and atherosclerosis, and it even increases your risk of cancer and fatty liver, and it even impairs your brain function over time and contributes to the development of dementia.
The Early Warning Window
So, there’s a study that was published in The Lancet where they showed that elevated insulin levels predicted type 2 diabetes up to 13 years before the diagnosis. So, this is a huge window of opportunity to reverse that process completely before too much organ damage sets in. You just need to look at the right test and act accordingly.
What Your Number Should Be
Now, as far as what’s considered normal, it really depends on which lab assay you’re using, and it can vary by age or sex or your BMI or body mass index. But in general, a fasting insulin level of about nine often suggests insulin resistance. And with my patients, I generally try to get that number to below five or six.
And the good news is that insulin resistance, if you catch it at this stage, is highly reversible. So, just by focusing on the basics, like reducing processed carbohydrates and sugars and maintaining a good mix of strength training and varying intensity cardio, and if you work on sleep, well, all that works remarkably well if you act early.
Test 3: Omega-3 Index
Okay, the next test I want to talk about is called the omega-3 index. And this is a test I recommend my patients to check at least periodically. And especially for those who take an Omega 3 or fish oil supplement. So, what is an Omega 3 index? Well, it’s a simple blood test that measures the percentage of EPA and DHA, which are the two key Omega 3 fatty acids in the membranes of your red blood cells.
So, basically, it just gives you a status of where you stand when it comes to Omega 3s. And you need to know your status. Because EPA and DHA are not just nutrients that you check off a list. They’re structural components of every cell membrane in your body, and especially in your brain and in your heart, and in the walls of your blood vessels.
And if your levels are too low, well, that will put you at an increased risk of heart disease and strokes and even sudden cardiac death.
What a Healthy Omega-3 Index Looks Like
So, what does a healthy Omega 3 index look like? Well, research points to a target of at least 8 to 12% because that’s the range consistently associated with cardiovascular benefits and neurocognitive brain benefits.
Now, most people hang around the 6% range, which puts them in the intermediate risk category. And if your index is 4% or lower, well, that’s the highest risk zone, which needs to be fixed as soon as possible. Because this level is associated with about a 90% higher risk of sudden cardiac death and the highest risk of progression to dementia compared to people with an index of 8% or higher.
Why Your Fish Oil Dose May Not Be Enough
Now, at this point, you may be thinking, well, this is why I take my fish oil for my heart health and my brain health. Well, here’s the problem. People respond differently to different doses of fish oil, and it really depends on the formulation and your individual biology. So, the standard dose written on the bottle may not be enough for you.
Also, the standard recommendation of two servings of fish per week often does not get you to that 8% index. So, most people will need an Omega 3 supplement to get into the desired range. But, here’s one thing we need to keep track of. We don’t want to take too much fish oil because high doses may increase your risk of atrial fibrillation, which is that serious irregular heart rhythm that can lead to strokes and heart failure.
And I actually go a little deeper into the dosing and the atrial fibrillation risk and how you should approach fish oil supplementation in another one of my videos, and I’m going to post a link to that below.
How to Check Your Omega-3 Index
So, if you want to check your omega-3 index, there’s a couple ways to do this. Your doctor can just order the test, or if your doctor is not familiar with it, you can actually order yourself online. A lot of the companies will just send you a home test kit with a finger prick blood test that you can just send back and you’ll get results in usually a few weeks.
Test 4: Vitamin D
Okay, the last test I want to cover is vitamin D, and I know everyone’s heard about vitamin D, but I still include it on this list because most people aren’t actually checking their blood levels. They’re just picking a dose of a supplement label and just assume that they’re covered, and that’s a big problem because as you’ll see, the level you land at matters a lot more than the dose that you take.
Why Vitamin D Matters
And this is why it’s so important. Vitamin D is not really a vitamin, it’s a steroid hormone that regulates over a thousand genes throughout your body, and vitamin D receptors are found in virtually every tissue and every organ.
So, you can find them in your immune cells and your brain and your heart and your gut, you name it. So, when you’re chronically deficient, it’s like a master control switch that’s turned down across hundreds of biological processes all at once. And we have studies that link low vitamin D levels to higher risk of heart disease and diabetes and autoimmune conditions like multiple sclerosis and rheumatoid arthritis.
And low vitamin D levels are also associated with faster cognitive decline and higher all cause mortality. So, the stakes are very real.
Why the Dose Alone Is Not Enough
Now, many people who do think about vitamin D, they just focus on the dose, and that’s a problem. There’s a recent study published in Nutrients that identified a statistical error in how the Institute of Medicine calculated the recommended daily allowance for vitamin D.
And when the data was reanalyzed correctly, the authors found that the RDA should have been set significantly higher than the previously recommended 600 international units. But, they also noted a substantial variability in the dose required based on your body’s weight. So, two people taking the same dose can end up at completely different levels.
So, the dose is meaningless without knowing the level and how your body responds to it. What we should be doing is dosing to a specific target. And there’s actually quite a bit of controversy on what the level should be, but with my patients, I typically recommend levels of at least 40 to 60. But, that target level really depends on individual medical history and what we’re trying to accomplish.
Vitamin D and Cancer Risk
With my patients, our focus is usually on longevity and health span. So, we put a lot of emphasis on trying to lower our overall cancer risk. And there’s a lot of studies, like this analysis of 2,300 women, that suggest that vitamin D levels of greater than 40 were associated with a 67% lower risk of all invasive cancers.
And there was a systematic review published last year that concluded that maintaining levels above 40 significantly lowers cancer risk and mortality from many different types of cancers. Now, once again, this is not a blanket recommendation, and your scenario may be different. So, I would definitely talk to your doctor to figure out where you need to be.
Now, to be clear, a lot of those cancer studies are based on observational data. So, as we often talk about, we can only infer association, but not necessarily causation. Meaning, when you look at observational data, people with higher vitamin D levels might simply be healthier, or they may spend more time outdoors, or they may be exercising more, or they may have lower body fat.
All of those things may lower your cancer risk just on their own. So, this is what we call a healthy user bias that we always have to control for with observational studies. To really test cause and effect, scientists do randomized control trials. And the data from randomized control trials is all over the place.
The VITAL Trial
In fact, the largest vitamin D trial, called the VITAL trial, actually found that supplementation with vitamin D did not lower risk of invasive cancer. But, when you look closer and parse out through the data in this trial, well, researchers found something very interesting. If you just look at people who had normal weight, well, those people had a 24% lower chance of developing cancer when they took vitamin D.
But, people who had obesity did not see that benefit, which actually makes sense because having excess weight or having obesity impairs your vitamin D bioavailability or response. So, the overall data may look like vitamin D did not help, but in reality, it may just mean that they did not reach high enough levels in those individuals.
So, bottom line is, don’t just pick a dose of vitamin D and forget about it. Your dose may change based on your weight or how much sunlight you’re getting, which changes from season to season. So, the only way to know is to check your levels periodically.
Frequently Asked Questions (FAQ)
Why aren’t routine labs enough to catch disease early?
The healthcare system, at least in the US, is built around waiting. By the time symptoms appear and routine labs start looking abnormal, the disease has often been building quietly for years, sometimes even decades, and organ damage has already set in.
What are the four blood tests that can detect problems early?
The four tests are high-sensitivity CRP (hs-CRP), fasting insulin, the omega-3 index and vitamin D.
What is the difference between regular CRP and high-sensitivity CRP?
Regular CRP is ordered for infections or autoimmune flares and only picks up large and obvious spikes of inflammation. High-sensitivity CRP is far more sensitive and can detect low-grade smoldering inflammation that causes no symptoms but has been quietly damaging your blood vessels for years.
What should my hs-CRP level be?
The goal is a number below one. If it is elevated, the goal is to find out why, because it is almost always something fixable upstream, such as insulin resistance, excess weight, disrupted sleep, poor dental health or emotional stress.
Why check fasting insulin instead of only fasting glucose or A1C?
Fasting glucose and A1C can look completely normal for years while insulin resistance develops in the background. Your pancreas overproduces insulin to keep blood sugar normal, so insulin levels climb first. A study published in The Lancet showed that elevated insulin levels predicted type 2 diabetes up to 13 years before diagnosis.
What is a good fasting insulin level?
It depends on the lab assay and can vary by age, sex and BMI. In general, a fasting insulin level of about nine often suggests insulin resistance, and with patients the aim is to get below five or six. If you catch insulin resistance at this stage, it is highly reversible.
What is the omega-3 index and what is a healthy level?
It is a simple blood test that measures the percentage of EPA and DHA in the membranes of your red blood cells. Research points to a target of at least 8 to 12%. Most people hang around 6%, which is the intermediate risk category, and an index of 4% or lower is the highest risk zone.
Is the dose of fish oil on the bottle enough?
Not always. People respond differently to different doses depending on the formulation and individual biology, and two servings of fish per week often do not get you to an 8% index. However, high doses of fish oil may increase the risk of atrial fibrillation, so you should not take too much.
Why should I check my vitamin D level instead of just taking a standard dose?
Substantial variability exists in the dose required based on body weight, so two people taking the same dose can end up at completely different levels. The dose is meaningless without knowing the level and how your body responds to it, and the right target level depends on individual medical history and goals. With his patients, the author typically recommends levels of at least 40 to 60.
Does vitamin D lower cancer risk?
Observational studies suggest that levels above 40 are associated with lower cancer risk, but they can only show association and may reflect healthy user bias. The largest trial, VITAL, found no overall reduction in invasive cancer, but people with normal weight had a 24% lower chance of developing cancer on vitamin D, while people with obesity did not see that benefit.
Conclusion
Disease builds quietly for years or even decades before symptoms appear or routine labs turn abnormal. Four blood tests can detect problems early: high-sensitivity CRP to measure inflammation, fasting insulin to spot insulin resistance, the omega-3 index to check your EPA and DHA status, and vitamin D to confirm that your level, not just your dose, is where it needs to be.
Getting these tests is only half the battle, because the same number can mean something different depending on your age, risk factors, other labs and family history. Pay attention to the interpretation, have an informed conversation with your doctor and advocate for yourself, because at the end of the day, no one has more at stake in your health than you do.
I hope this was helpful. Stay healthy.