Your Inflammation Test Is High. Are You Actually Inflamed?
In a Nutshell
High inflammation tests like ESR, CRP, hs-CRP, and ferritin are non-specific: they signal something is wrong but don't reveal cause, location, or true cardiovascular risk. Only hs-CRP is routinely used for longevity risk assessment, with values under 1 mg/L optimal, 1–3 mg/L intermediate, and above 3 mg/L higher risk—yet single results must be interpreted with context and trends, not chased with more tests. Trials like CANTOS show that lowering inflammation markers can reduce events only when specific pathways are targeted; generic attempts to lower CRP lack outcome evidence and may cause harm.
These notes were generated by AI and may contain inaccuracies.
Your inflammation is high. Is it damaging your heart and brain or is it a temporary response to an illness? The same abnormal result could mean both. There are many tests for inflammation and only one that is routinely used for longevity patients. To understand inflammation testing, it is necessary to go back to the origins of these tests.
Imagine a child with a fever and swollen, painful knees. Their doctor can see that the child is sick but needs more clues. There's a test doctors still use today where blood goes into a thin glass tube standing upright. First the column is filled with red. But then as the red blood cells fall towards the bottom they leave that straw colored plasma behind. The rate at which the tube changes from the red to the straw is something called the ESR. In one person that pale layer might grow really slowly. Another it grows quickly because the red blood cells are falling faster and that is a major clue in inflammation.
ESR stands for erythrocyte sedimentation rate. Erythro is red, cyte means cell. Sedimentation means settling. ESR is the rate at which the red blood cells settle. When inflamed, proteins in plasma will help red cells stack together. Because they're stacked together, they actually fall faster. So ESR isn't counting molecules of inflammation. It's just measuring a physical effect that inflammation and a couple of common conditions can change.
Inflammation helps fight infection and repair injury. Short-term infection has been felt before, whether it's from a cold, flu, or something else. Immune signals will create fever, body aches, loss of appetite, exhaustion, and poor concentration, the brain fog that makes a person feel sick. When thinking slows down during a flu, it doesn't mean that the brain itself is inflamed. It shows that the immune response elsewhere in the body can change how the brain is working during that time. It's when that response becomes excessive, persists too long, or turns against healthy tissue, like damaging blood vessels and organs, that it becomes a problem over time. Inflammation is linked with heart disease, metabolic dysfunction, autoimmune injury, and frailty. That is why it matters so much in longevity.
There is not just one single master inflammation level in the body, which is why no single blood test captures all of the types of inflammation. Even the earliest work on ESR showed that this one test is not that specific. In the 1890s, Polish physician Edmund Biernacki built that glass cylinder and timed the falling of the red blood cells. He also showed that anemia and a clotting protein called fibrinogen could also change that rate. He found differences in different feverish illnesses, including rheumatic fever. His great impact on medicine was that he turned this test into a repeatable clinical measurement. Later scientists like Robin Fahraeus used the test in pregnancy. Alf Westergren standardized it while studying tuberculosis. The history itself reveals the very limitation. Several different medical conditions can change the result. While Biernacki's name has largely unfortunately been forgotten, the test is still called a Biernacki reaction in Poland and it is still used everywhere.
It is known that pregnancy, kidney disease, certain types of antibody proteins, the shape of red blood cells, and even age itself can change the ESR number. However, a normal ESR can also give false reassurance if it is being asked to answer the wrong question. It doesn't clear someone of cardiovascular risk if they have high APOB or existing plaque. It will remain normal if inflammation is confined to a certain organ system such as the gut, skin, or joint.
In the gut, inflammation can cause cramping, urgent diarrhea, bleeding, weight loss. In a joint, it will cause familiar warmth, swelling, pain, and morning stiffness. In the skin, redness, swelling, or heat pain and itch might occur. What's really frustrating is the symptoms of inflammation themselves are very non-specific. Poor sleep, anemia, medications, and so many other problems can cause that same fatigue or slow thinking, that brain fog that a lot of people complain about. Bloating and diarrhea could be due to something else, not just an inflammatory GI problem. A rash doesn't necessarily mean autoimmunity or some sort of reaction, but it tells what organ needs closer attention.
ESR is good to check if there's something like a new swollen joint, morning stiffness lasting a long time, say over 30 minutes, recurring fevers, unexplained weight loss, or a persistent rash. Also, if there is a history of autoimmune or kidney disease, infection, anemia, or pregnancy.
Another really common inflammation test is CRP. This stands for C reactive protein. Unlike ESR, it's an actual protein that circulates in the blood. The liver releases a lot more of it when the immune signals report an infection, tissue damage, or another bodywide inflammatory response. CRP can rise quickly and fall quickly. So, it's really useful for detecting something recent. It doesn't tell what caused that problem.
However, HSCRP, which is seen a lot in the longevity sphere, is the high sensitivity CRP test, and it measures that same protein precisely at much lower levels. So those small stable differences can add so much interesting information for example about future heart disease risk. And yes this is the test that is ordered on basically all longevity patients.
The name came from a pneumonia experiment that seemed to identify one infection but turned out to be much more interesting. In 1930, William Tillett and Thomas Francis took the clear part of that blood again from patients with pneumonia and added one piece of the bacterium causing the illness. The mixture grew cloudy and a visible solid formed in the tube. And when that test was repeated on samples from patients who recovered, the reaction seemed to disappear. So this looked like a test for pneumococcal infection. But then the same reaction appeared in some other people with other types of infections and acute rheumatic fever. So the conclusion was the reaction was not specific to any one infection. It was reporting something the body does during various different illnesses. Scientists called that bacterial fragment fraction C. So that's where the name C reactive protein got its name. It doesn't stand for cardiac or chronic by the way. A lot of people think that and it doesn't stand for a catastrophe even if that's what it can feel like when it's abnormal.
CRP does more than just show where inflammation is. It takes part in the actual immune response. Immune cells detect an infection or damaged tissue and it sends signals to the liver. One of those signals is called interleukin 6 or IL6. The liver responds by releasing more CRP into the blood which attaches to chemical features found on some bacteria and damaged cells. And once they're stuck, they're like a flag placed on a target and that activates complement, which is a group of cascading domino effect blood proteins that helps immune cells clear whatever the problem is. So that's what the experiment in the 1930 tube was doing, what it captured, CRP binding to a piece of the bacterium being studied, which was pneumococcus.
This blood test doesn't tell anything about what causes a CRP to be elevated. It could be injury. It could be surgery. It could be infection and it could be an autoimmune flare. All that is known is that there's a problem and it can tell when it goes away.
Nowadays, CRP is used in two very different settings. In hospitals where patients could be very sick and in clinics where people are generally well. So, a patient recently came with a cardiac CRP result far above 10. So, this is in the bad range. And she was really terrified. And this is a young woman in her 30s, generally healthy, without any other issues. So, the process started chasing this down. It turns out that she had recently gotten an IV treatment at a med spa. The timing made it so suspicious. And luckily, the CRP response went away. It normalized after some time. It was a response to the treatment. It did resolve. So it tells that it probably wasn't something like a cardiovascular risk signal. Also, be careful of what is being received in a med spa.
HSCRP is basically the same thing as a CRP test, except it can detect tiny differences in a more normal range. It's not something usually ordered if worried about a big illness related result. When HSCRP is below one milligram per liter, that is what is called a lower relative risk or optimal if one would like to call it that. Between 1 and 3, that is a middle range. And above 3 is what is considered a higher relative risk. However, if something really high like the 10 or beyond is seen, then it's probably not just something like heart disease that's a problem. There's probably an acute illness or maybe a med spa treatment. If an HSCRP of 2 or higher is received on more than one test during a totally normal time, like not otherwise sick, that is a strong signal that there may be cardiovascular risk.
Ferritin is part of an iron panel, but it is also very helpful for detecting inflammation. It exposes the next failure of the one number idea as well. So when ferritin is high, maybe there is iron overload. It's actually not super common unless iron is being supplemented for some reason. But ferritin also rises with inflammation, liver injury or metabolic dysfunction. And it can look normal too when iron becomes less available. So if one thinks about it, it's just this sort of non-specific number. Once again, that's why inflammation is very frustrating sometimes because there's a lot of factors causing these tests results to look high or low.
Seven years after the CRP discovery, Czech scientist Vilém Laufberger isolated an iron-rich material from horse spleen and formed it into crystals. He called this crystal ferritin. So, ferritin is a microscopic storage cell made from 24 protein pieces. Thousands of iron atoms can be packed safely inside. So, the most obvious clinical use was for iron storage. A genuinely low ferritin is still one of the clearest clues there is for iron deficiency actually. But remember, it's kind of non-specific. So, the rest of a person's context must be understood.
If someone comes in and they have fatigue, shortness of breath, or restless legs, and they have a really low ferritin, the thought will be probably low iron. Same thing if there's heavy menstrual bleeding, frequent blood donation, digestive bleeding, or poor absorption due to an autoimmune disease such as celiac or inflammatory bowel disease, or even some folks who have intestinal surgery history, they might have true iron deficiency.
But what if the ferritin level is normal or even high? High ferritin can reflect iron overload. It can also rise during infection, inflammatory disease, metabolic dysfunction, like mentioned, liver harm, kidney disease, or even cancer. So one could tell if not careful, it's easy to freak out due to a number of possibilities with one abnormal number.
Take one patient who was actively ill with an acute illness. Their CRP and ESR rose. So those are some of the prior inflammation tests and their serum iron fell. Transferrin saturation fell. That's another result on an iron panel. So did TIBC, the blood's iron carrying capacity, but the ferritin looks normal. So if only the serum iron is looked at, one might conclude that the body's iron stores were empty. You've run out of iron. If only ferritin is looked at, one might determine that the iron status was totally fine. And neither is the true picture.
During inflammation, the liver will produce something called hepcidin. Hepcidin reduces iron absorption and keeps more iron inside their storage cells. So circulating iron becomes less available even when the body has not actually run out of stored iron. So the body has not run out of iron in this situation. It's just changed where the iron is sitting at the moment and how available it is. There's some theories about why this happens during illness, by the way, but that rabbit hole will not be gone into at the moment. The point is, iron status should not be checked if otherwise sick because it's going to be impacted by a lot of things going on.
Another real patient was totally well, really fit guy actually, and everything looked fine on their very extensive 100 plus biomarker lab tests panel. The only outlier was ferritin. It was really high. With a really high ferritin, if a high transferrin saturation and a family history of some condition like hemochromatosis or known iron overload is also seen, then the thought would be, okay, this is something to do with the iron. But this person had no such history. It didn't tell anything about the iron status. A deeper look had to be taken. When a deeper look was taken, it turned out that this really fit, healthy guy actually had fatty liver disease. Turns out metabolic dysfunction had caused the ferritin to get much higher. And it could visibly be told by looking at the liver itself.
So just like all the other inflammation tests, ferritin can be impacted by a number of things from alcohol exposure to metabolic disorder and liver injury, infection, systemic inflammation, kidney disease, cancer, iron supplements or infusions, and true iron overload.
By now, a pattern has probably started to be seen. It turns out that a lot of these inflammation tests that are received are a very non-specific signal. So they're sensitive for something going on, but they're not super specific. And that's how they are ordered. They are used for this reason. In the longevity clinic, an HSCRP will be tested. If it is elevated, then it is known that a harder look must be taken.
How HSCRP started being used in this way goes back to the 1990s, when Paul Ridker and colleagues opened stored samples from the Physicians Health Study. The men had been healthy when the samples were collected and after eight years some of them had a first heart attack or an ischemic stroke due to atherosclerotic disease. So the question was could blood be taken from years before a stroke or a heart attack and predict something? It turns out that the measured baseline CRP in 543 men who later had a stroke or a heart attack compared to 543 controls who did not had differences. For those who had the heart attack, the average baseline CRP was about 1.5 milligrams per liter. For those who didn't, it was about 1.1. So one could tell that's like a very small difference. Actually, the ranges also overlapped and no single result could identify a person very clearly who would have the heart attack.
However, if they looked across the population, men in the highest CRP quartile had almost three times the risk of myocardial infarction, that's a heart attack, and about twice the risk of an ischemic stroke compared with men in the lowest quartile. CRP is a really interesting test. Really big differences can report on an acute illness, but much smaller, more stable differences could give a lot of important information about future cardiovascular risk. And high sensitivity assays made the low concentrations of these more normal CRP levels easier to measure precisely.
The JUPITER study tested what happened when treatment was offered to people selected partially because of their HSCRP. JUPITER enrolled almost 18,000 apparently healthy adults whose LDL cholesterol was below the treatment threshold used at the time but whose HSCRP was at least 2 milligrams per liter. Then they used rosuvastatin to reduce the chance of major cardiovascular events. Essentially this study was showing that using HSCRP one could better identify a group that had higher risk of cardiovascular disease and may benefit from statin treatment even if their LDL cholesterol which is the more conventional test that would be received wasn't that high. Just as a side note this did not prove that lowering CRP itself caused any benefits. Statins actually do lower atherogenic lipoproteins, so APOB, LDL, so forth. But they also affect inflammatory signaling. A future episode will be about things that can reduce inflammation and the impact on long-term longevity health.
The field of cardiology, which is amazing because of how much evidence it relies on for their guidelines, is taking HSCRP a lot more seriously, but never by itself. In fact, a 2025 American College of Cardiology scientific statement argued for a larger role in risk assessment using HSCRP. It's still just one of the many tests recommended for gauging someone's risk. So, LDL, non-HDL cholesterol, selective APOB testing, one time LP little A and a coronary calcium when useful is what is recommended by that body. All of the above is recommended if possible to get.
As a quick review, APOB tells about the number of atherogenic particles available to enter the artery wall. LP little A is a largely inherited risk, a type of APOB particle. And HSCRP doesn't tell anything about those things, but it tells about inflammation, which is something that occurs once particles get into the walls and then the inflammation starts when the immune system attacks these. Also, just so it is not forgotten, family history is so important. People are seen with all kinds of funny numbers on their labs and their family history is remarkably clear of heart disease, strokes, and so forth. There are factors out there that are not easy to test for whether they're genomic or something to do with interactions with the external world. It's very hard to tell and predict for a single individual what will happen. And the very best way to tell actually is to look at the family.
Sometimes people come with giant reports filled with inflammation markers. They ordered more inflammation tests because they just wanted one simple answer. Is there hidden inflammation aging faster? ESR, cytokines, fibrinogen, glyA, neutrophil ratios, some kind of proprietary score that combines everything into a clean number. Could one of these new tests reveal the slow inflammation that CRP might be missing or measure how fast the immune system is aging?
One particular test is the glyA test. So it sounds like glucose or glycation, but it actually measures neither of the above. Picture several proteins in the blood that have short sugar chains attached to them. The lab uses the same basic physics behind the technology of MRI to detect the signal from the sugar chains on acute-phase proteins and that combined signal is called glyA because it blends information from several proteins. GlyA tends to vary less from one draw to the next than HSCRP. Unlike HSCRP, which can kind of bounce around sometimes if repeat tests are received in large groups of people, higher glyA is associated with disease, diabetes, severe inflammatory disease, cancer, and earlier death. It still isn't super specific. It doesn't tell where the inflammation is coming from. And there aren't really routine glyA cutoffs that tell a well person what to do or what kind of treatment to even pursue.
Also, just because it comes up a lot, glyA is different from something called a glycan age test, which might have been seen out there in the longevity world. Those glycan age tests usually study sugar chains attached to immunoglobulin G or IgG, one of the main antibodies. So, that pattern also changes with age, but it also shifts with things like weight changes, hormone changes, illness, and other things that just happen in a normal person's biology. Researchers are still working even now to turn various patterns into some sort of estimate about one's health. That estimate may help study immune aging, but it cannot yet tell an individual how old the immune system is, what treatment to choose, or whether a lower result means that one will live longer. And even though there are clinics that use it this way, if the score is managed to be moved after trying some sort of intervention, it doesn't actually prove yet that the intervention made the person younger in a way that improves health. The field is still very much in the research realm when it comes to these types of tests.
Inflammaging is a term describing chronic low-grade inflammatory changes that become more common as people age. So, across populations, patterns involving CRP, IL6, glyA and other signals have been linked with frailty, more chronic disease, loss of function, and earlier death. All the nos in longevity goals. But no single test can diagnose inflammaging. And there's no agreed upon optimal panel or set of results or ranges. Like everything else that is done when testing for inflammation, an abnormal result shouldn't lead to panic. It should just lead to more questions. If there's a slightly elevated inflammatory test result, other clues should be looked for. Maybe there's a flu or swollen joint. Or maybe weight has been gained from fat, or more junk foods have started being eaten, or maybe blood pressure has changed. Maybe sleep hasn't been good or there is sleep apnea or there is smoking or being around a smoker. So basically, inflammation tests are used to give clues and to examine what might be able to be changed.
If nothing else is remembered, don't go chasing more inflammation tests if there's some sign of inflammation. If there's already one positive test, it usually doesn't mean that 10 more are needed. It usually means a different type of test is actually needed to figure out what's causing that inflammation test to be abnormal. And sometimes it's not just a very expensive blood panel at all. Maybe it's looking for signs like persistent diarrhea with or without bleeding, weight loss that's inexplicable or not purposeful, or maybe some sort of personal or family history of an inflammatory disease, autoimmune or otherwise.
A quick note about timing tests. If there are two people with the exact same HSCRP, say it's a little bit high, 4.5 milligrams per liter, one person might be totally normal and the other person might have some real heart disease risk and the difference might be just timing. If this blood test is drawn after a hard workout, for example, there might be an elevation in HSCRP. So that's why not only do recent illnesses need to be watched out for, but recent tough workouts also need to be watched out for. This is also why it's important to follow trends more than react to any one test result.
An interesting situation comes up all the time. So, if CRP can predict heart disease risk and a treatment lowers CRP level, does heart disease risk fall too? Questions like this should be asked because a lot of supplements, diets, treatments are promoted because they lower an inflammation marker. They're not actually claiming to lower heart disease risk or maybe they shouldn't because there's no evidence to prove that. The real answer, of course, is kind of complicated. Human genetic studies suggest that CRP itself acts more like a reporter than the main causal molecule. That means upstream must be moved and inflammatory pathways targeted.
There are three major trials that separated the pathway, the marker, and the patient outcome. In CANTOS, people who already had a heart attack and still had an HSCRP of at least two received something called canakinumab, which blocks IL1 beta. At the 150 milligram dose, recurrent cardiovascular events fell by 15% compared to placebo even without lowering their LDL cholesterol. So there was a real cardiovascular benefit from targeting a defined inflammation
The CANTOS trial demonstrated that targeting a specific inflammation pathway provided real cardiovascular benefit, but fatal infections increased and all-cause mortality did not improve, indicating both benefit and harm from the intervention.
Low-dose methotrexate was tested in people with stable atherosclerosis plus diabetes or metabolic syndrome. The drug is an anti-inflammatory agent, but in this population the pathway markers did not change and cardiovascular events did not decrease.
The ZEUS trial tested ziltivekimab, an antibody against the IL-6 ligand, in over 6,300 people with established cardiovascular disease, chronic kidney disease, and hs-CRP of at least 2. The drug engaged with the intended pathways and both free IL-6 and hs-CRP levels fell as expected. However, serious infections occurred, similar to the CANTOS trial findings.
The ZEUS trial did not prove that inflammation is irrelevant to heart disease. It showed that in this specific IL-6 lowering strategy applied to this particular high-risk population, the pathway was addressed and biomarkers improved without improving the actual clinical outcomes that matter, while adding the risk of infection.
These trials provide hard evidence that sometimes lowering a number does not improve outcomes, and sometimes lowering a bad number can actually cause bad outcomes. Caution is warranted before pursuing generic supplements or treatments that claim to lower CRP or inflammation, as the goal should be true healthcare outcomes such as decreasing actual chance of heart attack.
Longevity requires knowledge about inflammatory status, and hs-CRP remains the go-to test for most prevention patients. When an abnormal result occurs, it is non-specific and requires further investigation. Random attempts to reduce inflammation should be avoided because they might cause harm without delivering the actual benefit that matters.
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