Between the results sheet of a blood test and what it means for your future health, there is a work of interpretation that few patients know about. This article presents blood biomarkers by family, distinguishes a standard blood test from a metabolomic panel and offers guidelines for reading your results without over-interpreting them.
What is a blood biomarker?
A blood biomarker is an objectively measurable characteristic in the blood that provides information about a normal biological process, an early or established disease, or the response to an intervention. Glucose, LDL cholesterol, creatinine and C-reactive protein (CRP) are familiar examples. A biomarker is not a disease: it is a clue, and its value depends on the context.
Biomarkers are usually classified according to how they are used:
- diagnostic, to confirm or rule out a disease in a person who has symptoms;
- prognostic, to estimate the likely course of a known disease;
- predictive, to anticipate the response to a treatment or a change in habits;
- monitoring, to check the effect of an action over time.
In prevention, for a healthy adult, most blood biomarkers are risk markers: in large populations, their level is associated with a higher or lower probability of developing a disease in the following years. Robust at the population level, this association remains uncertain at the individual level: that is the starting point of any honest reading of a blood test.
A useful clarification, because online searches mix these topics: tumor markers and blood biomarkers for Alzheimer’s disease belong to a specialized diagnostic setting, in people who have symptoms or an identified risk. They have no place in a prevention check-up for adults without symptoms; ordering them “just to see” exposes you to overdiagnosis.
What are the main families of blood biomarkers?
The blood biomarkers useful in prevention fall into seven main families: lipids and lipoproteins, blood glucose and glycated hemoglobin, inflammation, kidney function, liver function, fatty acids and amino acids, and vitamins. Each family provides information about a different system; reading them together is what makes sense. We deliberately do not give reference values: they vary by laboratory, method, age and sex, and interpreting them is the doctor’s job.
| Family | Markers (examples) | What they reflect | Why they matter in prevention |
|---|---|---|---|
| Lipids and lipoproteins | Total cholesterol, LDL, HDL, non-HDL, triglycerides, apolipoprotein B; by NMR: particle number and size by class | Fat transport and the load of particles likely to deposit in the arteries | Non-HDL cholesterol is a SCORE2 variable; particle detail (number, size, composition) refines the profile beyond LDL alone |
| Blood glucose and glycated hemoglobin | Fasting glucose, HbA1c; by NMR: glucose, lactate, pyruvate, citrate | Blood sugar regulation; HbA1c summarizes average blood glucose over the previous weeks | Spotting a trajectory toward type 2 diabetes before the disease threshold, when habits have the most impact |
| Inflammation | CRP (C-reactive protein), GlycA (glycoprotein acetyls, measured by NMR) | Chronic low-grade inflammation, distinct from the acute inflammation of an infection | Associated with cardiovascular and metabolic risk; GlycA is an integrated marker, more stable over time than a single CRP |
| Kidney function | Creatinine, estimated glomerular filtration rate (eGFR), urea, cystatin C | The kidneys’ ability to filter the blood | Early impairment is silent and increases cardiovascular risk; it calls for caution with certain medications |
| Liver function | AST, ALT, GGT, alkaline phosphatase, bilirubin | Liver damage or overload (fat, alcohol, medications) | Metabolic fatty liver disease is common and silent for a long time; enzymes point toward a targeted work-up |
| Fatty acids | Omega-3, omega-6, saturated and monounsaturated fatty acids, ratios between families (NMR) | The composition of circulating fats, a partial reflection of diet | Associated with cardiometabolic risk and modifiable through diet: a monitoring marker |
| Amino acids | Branched-chain amino acids (leucine, isoleucine, valine), alanine, glutamine, tyrosine, phenylalanine, histidine (NMR) | Protein metabolism and insulin sensitivity | Some are associated with type 2 diabetes risk in cohorts; they complement the reading of blood glucose |
| Vitamins and minerals | Vitamin D, vitamin B12, folate, ferritin, iron | Stores and deficiencies | Useful when the context warrants it (diet, symptoms, age); no routine testing in prevention for adults without risk factors |
NMR stands for nuclear magnetic resonance: the technique that quantifies lipoproteins by class, fatty acids and metabolites in a single run; we explain it in our article on NMR metabolomics.
What does a standard blood test include, and what does it show?
A standard blood test, as prescribed in general practice, measures a limited set of parameters chosen by the prescribing doctor according to the situation: typically ten to twenty measurements. It answers specific questions and has proven its worth: anemia, diabetes, dyslipidemia, kidney or liver impairment.
Its strengths are real: standardized, reimbursed with a prescription, available in any medical laboratory, interpretable by any doctor. Its limits stem from how it is built: each parameter is measured separately, it only measures what the prescribing doctor requested, and it is expressed as “normal / abnormal,” which poorly captures gradual changes in a healthy person.
To find out what an extended blood test includes, how much it costs with or without a prescription and how it is reimbursed, see our article on the comprehensive blood test. As a reminder, Mon bilan prévention, France’s national prevention check-up program, fully covered (100%) by French National Health Insurance (Assurance Maladie) at the four key ages, is a 30- to 45-minute consultation without laboratory tests: it identifies risks and builds a plan, with a blood test coming afterward if the professional considers it useful.
What does a 249-biomarker metabolomic panel add?
An NMR metabolomic panel quantifies 249 biomarkers simultaneously from a single sample, whereas a standard blood test measures a limited set. It does not replace it: it broadens the scope to measurements that routine laboratory testing does not provide, in particular detailed lipoproteins, fatty acids, amino acids and low-grade inflammation (GlycA).
This panel, developed by Nightingale Health (Helsinki), has been applied at scale in the British UK Biobank cohort: the analysis of 118,461 participants produced an “atlas” of associations between these 249 biomarkers and more than 700 common diseases (Julkunen et al., Nature Communications, 2023). A striking result: circulating lipids and metabolites are risk markers well beyond cardiometabolic diseases (infections, certain cancers, joint conditions, mental health).
Three other studies shed light on their value in prevention:
- Predicting several diseases from a single sample. In 117,981 UK Biobank participants, validated in four cohorts, a metabolomic profile combined with age and sex matched or outperformed established predictors for the 10-year onset of fifteen of the 24 diseases studied, and added information to clinical variables for eight of them, including type 2 diabetes, dementia and heart failure (Buergel et al., Nature Medicine, 2022).
- A profile associated with mortality. In 44,168 people from twelve cohorts, fourteen independent biomarkers were associated with all-cause mortality and predicted 5- and 10-year mortality better than conventional risk factors (Deelen et al., Nature Communications, 2019).
- Understanding the mechanisms. The genetic characterization of 233 biomarkers in 136,016 participants from 33 cohorts identified more than 400 regions of the genome that influence them, a resource for distinguishing cause from correlation (Karjalainen et al., Nature, 2024).
These results apply at the level of the populations studied. A panel does not “detect” these diseases in a given person: it refines a risk estimate, which is different and already useful.
Which blood biomarkers are truly predictive in prevention?
The blood biomarkers best established as risk markers in healthy adults are those included in validated scores: non-HDL cholesterol for cardiovascular risk, blood glucose and HbA1c for diabetes risk, creatinine and eGFR for the kidneys. Metabolomic markers come next, as complements whose added value has been measured in cohorts.
The SCORE2 score, published in 2021 by the European Society of Cardiology, estimates the 10-year risk of a fatal or non-fatal cardiovascular event in people aged 40 to 69 from five variables: age, sex, smoking, systolic blood pressure and non-HDL cholesterol. It includes only one blood measurement: that is what makes it usable everywhere, and the reason why dozens of other measurements (detailed lipoproteins, inflammation, fatty acids) can add information for some people. We explain this reading in detail in our article on 10-year cardiovascular risk.
Among the markers in the NMR panel, three stand out in prevention: the number of lipoprotein particles carrying apolipoprotein B, which reflects the atherogenic load beyond LDL cholesterol alone; GlycA, an integrated marker of chronic inflammation; and the extended glycemic profile (glucose, lactate, branched-chain amino acids), associated with the trajectory toward type 2 diabetes. Their value lies in their combination, interpreted in the context of the person.
How do you read a blood test without over-interpreting it?
Reading a blood test means putting each value back into its context rather than ticking off the results outside the range. Six guidelines help avoid the most common mistakes.
- A reference range is not a health standard. It describes the spread of values in a reference population; a value slightly outside it is not a disease, and a value inside it is not a guarantee.
- Variability is twofold. Biological (fasting, time of day, recent physical activity, a minor infection, menstrual cycle, medications) and analytical (method, laboratory). Two measurements a few days apart normally differ.
- A single data point says little; a trend says more. Comparing with your previous results, in the same laboratory if possible, is more informative than a single value.
- The more you measure, the more you find. In a panel of several hundred biomarkers, a few atypical values are expected by chance alone; interpreting them one by one leads to unnecessary tests.
- Association is not causation. A marker linked to a disease in a cohort may only be a bystander; changing it does not always change the risk.
- A blood test answers a question. A test ordered “just to see” mostly produces questions.
These guidelines do not mean you shouldn’t read your own results, quite the opposite: a patient who understands what they read takes a better part in decisions. They are a reminder that interpretation is a medical act.
What is the doctor’s role in reading biomarkers?
The doctor’s role is to turn a list of biomarkers into an understandable risk estimate, then into a prioritized action plan, taking into account what the laboratory cannot see: family history, lifestyle, symptoms, treatments, the person’s priorities. The doctor is also the one who decides not to investigate an isolated value of no consequence: quaternary prevention in action.
In consultation, we proceed in three steps: check what calls for immediate action (rare in healthy adults), place the overall risk using validated scores, then identify one or two modifiable levers that matter for this person. The blood test is never the end of the reasoning; it is one piece of it. This is the logic of personalized health: tailoring prevention to each person’s profile without multiplying tests. Fellow physicians who wish to integrate extended panels into their practice will find our approach on the Sokrate for doctors page.
Key takeaways
- A blood biomarker is a measurable clue, not a disease; in prevention, biomarkers are mostly risk markers whose value is statistical.
- Seven families cover the essentials: lipids and lipoproteins, blood glucose and HbA1c, inflammation, kidneys, liver, fatty acids and amino acids, vitamins.
- A standard blood test measures a limited set of parameters; the NMR metabolomic panel quantifies 249 from a single sample, with predictive value documented in UK Biobank.
- A value outside the range is not a diagnosis; the trend over time and the context matter more.
- Interpretation is a medical act: the doctor prioritizes and decides, including deciding not to investigate.
What Sokrate lets you do
The Sokrate service prepares your prevention check-up online with an adaptive self-assessment questionnaire (Sokrate 360, nine dimensions), then a doctor writes and signs your Personalized Prevention Plan, which is sent to your regular doctor (médecin traitant) unless you object. As an option, an NMR metabolomic analysis of 249 biomarkers, performed on the Nightingale Health platform, is interpreted by a doctor and explained in plain language: risk estimate, priorities, modifiable levers. A coordination nurse provides follow-up. See how the Sokrate pathway works or join the waitlist.