Inflammation Markers in Blood Tests Explained: hs-CRP, ESR, IgG Glycans and What They Really Measure

Blood tests for inflammation can come back completely normal while chronic, low-grade inflammation quietly drives up biological age in the background. That is how two people with identical CRP results end up aging at very different speeds. The reason comes down to timescale: standard inflammation panels are built to catch a spike happening right now, while a different kind of marker, IgG Glycans, is built to track a slower trend running underneath it. In this article, we will look at what each one is actually measuring, starting with the test most people already know. 

If you want the fuller picture of that slower trend first, read our article on Chronic Inflammation & Inflammaging: The Hidden Driver of How You Age.

What blood tests for inflammation actually measure

C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are the traditional gold standards for catching an immediate immune response. CRP rises within hours of an acute trigger, such as an infection, injury, or flare of an existing condition, then falls back down once the trigger resolves. ESR works on a similar principle: it tracks how quickly red blood cells settle when inflammatory proteins are elevated, and it responds a little more slowly than CRP does. Plasma viscosity (PV) picks up a comparable signal by measuring how those same proteins thicken the blood.

All three are excellent at what they were designed for: flagging a sudden, active immune event. What they were not designed for is capturing a low, persistent hum of inflammation that never spikes high enough to move the needle on an acute-phase test, but still accumulates year over year.

Why timescale changes everything

CRP and ESR measure whether something acute is happening right now. They rise fast when triggered and fall back down once the trigger resolves, which makes them accurate for the moment they're taken but blind to anything outside that window.

IgG Glycans measure something different: the cumulative inflammatory load the immune system has been carrying over months and years. Rather than spiking in response to a single event, glycosylation patterns on IgG antibodies shift gradually as chronic, low-grade inflammation, commonly known as inflammaging, builds up.

That difference matters because inflammaging is exactly the kind of slow-burn process CRP and ESR are structurally unable to catch. A person can test normal on CRP every year for a decade while their underlying inflammatory burden, and their biological age, keeps climbing.

"A lot of studies are done just as a snapshot, and we never really know whether it's cause or effect, or which way round it is. But to have this amazing picture through a couple of decades really reinforces how important it is, and how glycans are really showing how biological age changes during that time."

— Prof. Tim Spector, Professor of Genetic Epidemiology, King's College London; Scientific Co-Founder, Zoe

Why a "normal" CRP doesn't mean a healthy inflammatory profile 

A normal CRP result rules out an active acute event at the moment of testing. It does not rule out the cumulative, systemic inflammation that tracks with faster biological aging. This is the gap that matters most for anyone using blood tests for inflammation to inform a longevity strategy rather than to diagnose a single illness: the acute markers were never built to answer the question "how fast am I ageing," because that was never their job.

This is also why relying on a single CRP or ESR reading as a proxy for overall inflammatory health can be misleading. A one-off snapshot cannot tell the difference between someone with genuinely low systemic inflammation and someone whose chronic inflammation simply has not spiked into acute-phase range recently.

When acute markers earn their place, and when they don't

CRP, ESR, and PV remain the right tools for what they do well: catching a flare of rheumatoid arthritis, ruling in or out an active infection, or monitoring how a specific inflammatory condition responds to treatment over a matter of weeks. For those specific, event-driven questions, acute markers are fast, cheap, and clinically proven.

For a different question, how quickly the immune system itself is aging, and whether day-to-day habits are helping or hurting, IgG Glycans are built for a longer view. Instead of one moment in time, they reflect the accumulated inflammatory load the immune system has been carrying, which is the more relevant number for anyone trying to manage inflammaging proactively rather than just responding to it after a flare.

Where IgG glycans and GlycanAge fit in

Chronic inflammation drives an overactive immune response that accelerates the aging process and raises the risk of age-related illness. The GlycanAge biological age test reads IgG glycosylation patterns from a single at-home finger-prick blood spot, translating that chronic inflammatory signal into a biological age number that reflects how the immune system is actually holding up, distinct from chronological age.

Because the test is tracking a slow-moving signal rather than an acute one, retesting is where it becomes genuinely useful. Two tests taken six to twelve months apart, in line with how long lifestyle changes typically take to show up in immune ageing markers, reveal whether a given intervention is actually reducing inflammatory burden or just feeling like it is. 

"If I change into a healthier lifestyle, it actually goes down, so I can say I'm saving healthy years of my life. The good thing about GlycanAge is that it's responding to interventions. It can tell me whether what I'm doing is good for me or not."

— Prof. Gordan Lauc, Co-Founder and Chief Scientific Officer, GlycanAge; Professor of Biochemistry and Molecular Biology, University of Zagreb 

Custom plans are available for people making more aggressive interventions, and repeat testing works just as well for tracking whether a specific treatment plan is having a measurable effect over time.

All packages come with a complimentary consultation with a certified research and healthcare expert to help translate the result into next steps.

What actually lowers inflammatory load

Reducing chronic inflammation is less about a single supplement and more about a handful of levers that GlycanAge's own research keeps surfacing as consistently effective.

"I'm a doctor who has transferred from prescribing pills to prescribing lifestyle, and for me that's really at the core of happy, healthy, long living. I measure biological age in all of my clients now as a critical piece of data that we should all be mapping to."

— Dr. Alka Patel, GP, Lifestyle Medicine Doctor, Author, and Podcaster

Caloric restriction is the most consistently anti-inflammatory dietary intervention in GlycanAge's provider data, ahead of any single diet pattern. Marine omega-3s, specifically EPA and DHA rather than plant-based sources, have published data showing a measurable effect on glycan-linked inflammation. Sleep quality and stress load also move the needle, since both feed directly into the same immune pathways that IgG Glycans are reading.

The point of retesting after six to twelve months is to see which of these levers is actually working for a given person, rather than guessing.

The right test for the right question

CRP, ESR, and PV are not going anywhere, and they shouldn't. They are still the fastest way to catch an acute inflammatory event. But for anyone asking a longevity question rather than an urgent medical one, IgG Glycans answer a question acute markers were never designed to touch: not "is something wrong right now," but "how fast is my immune system aging, and is that trend moving in the right direction."

For a direct look at that number, the GlycanAge biological age test is a good place to start, and clinicians who want to fold this into patient monitoring can find more detail on the healthcare provider page.

Frequently asked questions (FAQs)

Can I have a normal CRP and still have high biological age from inflammation?

Yes. CRP only reflects acute, in-the-moment inflammation. Chronic, low-grade inflammation, inflammaging, can accumulate for years without ever pushing CRP out of its normal range.

What's the difference between CRP/ESR and IgG Glycans? 

CRP and ESR spike in response to a specific trigger and fall once it resolves. IgG Glycans shift gradually with cumulative inflammatory load, making them better suited to tracking long-term trends rather than single events. 

How often should I retest inflammatory markers for longevity tracking? 

For acute markers like CRP, retesting timing depends on the specific condition being monitored. For IgG Glycans, six to twelve months between tests gives lifestyle changes enough time to show a measurable effect. 

Can lifestyle changes actually lower chronic inflammation? 

Yes. Caloric restriction, marine omega-3 intake, sleep quality, and stress management have all shown measurable effects on inflammatory load, and retesting is how you confirm whether a specific change is working for you. 

External sources

• https://pubmed.ncbi.nlm.nih.gov/9971870/ — Gabay C, Kushner I. Acute-phase proteins and other systemic responses to inflammation. N Engl J Med. 1999;340(6):448-454. 

• https://pubmed.ncbi.nlm.nih.gov/29094869/ — Bray C, Bell LN, Liang H, Haykal R, Kaiksow F, Mazza JJ, Yale SH. Erythrocyte sedimentation rate and C-reactive protein measurements and their relevance in clinical medicine. WMJ. 2016;115(6):317-321.

• https://pmc.ncbi.nlm.nih.gov/articles/PMC6582449/ — Watson J, Jones HE, Banks J, Whiting P, Salisbury C, Hamilton W. Use of multiple inflammatory marker tests in primary care: using Clinical Practice Research Datalink to evaluate accuracy. Br J Gen Pract. 2019;69(684):e462-e469.

• https://bmjopen.bmj.com/content/10/10/e036027 — Watson J, Whiting P, Salisbury C, Banks J, Hamilton W. Raised inflammatory markers as a predictor of one-year mortality: a cohort study in primary care in the UK using electronic health record data. BMJ Open. 2020;10(10):e036027. 

• https://pmc.ncbi.nlm.nih.gov/articles/PMC9535357/ — Deriš H, Tominac P, Vučković F, Briški N, Astrup A, Blaak EE, Lauc G, Gudelj I. Effects of low-calorie and different weight-maintenance diets on IgG glycome composition. Front Immunol. 2022;13:995186. 

• https://pubmed.ncbi.nlm.nih.gov/34132788/ — Stupin A, Cvetko A, Kralik G, Mihalj M, Sušnjara P, Kolobarić N, Breskić Ćurić Z, Lukinac AM, et al. The effect of n-3 polyunsaturated fatty acids-enriched hen eggs consumption on IgG and total plasma protein N-glycosylation in healthy individuals and cardiovascular patients. Glycobiology. 2021;31(9):1163-1175. 

• https://pmc.ncbi.nlm.nih.gov/articles/PMC4049143/ — Krištić J, Vučković F, Menni C, Klarić L, Keser T, Beceheli I, et al. Glycans are a novel biomarker of chronological and biological ages. J Gerontol A Biol Sci Med Sci. 2014;69(7):779-789.