Top Applications of Biomarkers in Medicine and Beyond

Every time a doctor orders a blood test, checks a troponin level after a suspected heart attack, or uses a rapid antigen strip to confirm COVID-19, they are relying on biomarkers. These measurable biological signals – molecules, proteins, genes, or even physiological readings – are among the most powerful tools in modern medicine. According to a comprehensive review published in PMC, biomarkers are used to personalize healthcare, analyze pharmaceutical safety, and monitor disease development. Their applications now reach far beyond the clinic – into sports integrity, drug discovery, and environmental health. This post explores three of their most impactful application areas: disease diagnosis, clinical monitoring and prognosis, and therapeutic development including anti-doping.

Disease diagnosis: detecting illness with precision 🔗

The most immediate application of biomarkers is identifying whether a disease is present. The FDA-NIH BEST Resource defines a diagnostic biomarker as one used to detect or confirm the presence of a disease or condition, or to identify individuals with a specific disease subtype. Diagnostic biomarkers must perform with high sensitivity (correctly identifying those who are sick) and high specificity (correctly ruling out those who are not).

COVID-19: antigens and proteins at the frontline 🔗

The COVID-19 pandemic demonstrated, at global scale, just how critical biomarkers are for disease diagnosis. Rapid antigen tests detect specific SARS-CoV-2 proteins directly from nasal swabs, allowing point-of-care diagnosis within minutes. Beyond antigens, inflammatory biomarkers such as C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin, and ferritin have been studied for their ability to predict disease severity and the risk of complications like acute kidney injury in hospitalized patients. These markers help clinicians distinguish mild infection from severe systemic disease quickly and objectively.

Malaria: from blood smears to circulating antigens 🔗

For malaria, diagnosis relies on a combination of biomarker-based techniques. A complete blood count revealing anemia and thrombocytopenia, a Giemsa-stained blood smear showing Plasmodia at different developmental stages, and elevated lactate dehydrogenase indicating hemolysis are all standard diagnostic markers. Rapid diagnostic tests that detect circulating malaria antigens have made diagnosis possible even in low-resource settings where microscopy is unavailable – a major public health advance in endemic regions.

Chronic kidney disease: reading glomerular function 🔗

Chronic kidney disease (CKD) is frequently silent in its early stages, making biomarkers especially critical for detection. Glomerular filtration rate (GFR) remains the primary marker of kidney function, but because direct GFR measurement is time-consuming, clinicians rely on estimated GFR (eGFR) calculated from serum creatinine and cystatin C levels. Albuminuria – the presence of albumin in urine – often precedes a measurable decline in eGFR and is strongly associated with disease progression. Microalbumin (mALB) is a sensitive biomarker for early renal damage, particularly in diabetic and hypertensive nephropathy, and is widely used for both diagnosis and monitoring. Newer markers like kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) offer the promise of detecting kidney injury even before creatinine levels rise.

Cancer: protein markers and imaging biomarkers 🔗

In oncology, biomarkers take multiple forms. Prostate-specific antigen (PSA) is a well-established protein biomarker used to screen for and monitor prostate cancer. In Alzheimer’s disease, amyloid-beta and tau proteins facilitate early diagnosis and monitoring, while cardiac troponin is the gold-standard diagnostic marker for myocardial infarction. Imaging biomarkers – derived from CT, PET, and MRI scans – are also classified as biomarkers when they provide objectively measurable data about disease state, allowing clinicians to assess tumor size, tissue changes, or organ function without invasive procedures.

Clinical monitoring and prognosis: tracking disease over time 🔗

Once a disease is diagnosed, the role of biomarkers shifts from detection to monitoring. Prognostic biomarkers predict how a disease will evolve – whether it will worsen, stabilize, or respond to treatment. Prognostic biomarkers give a prediction of the prognosis or course of a disease, such as its recurrence or response to therapy. This information directly guides clinical decision-making.

Cardiovascular disease: LDL cholesterol and CRP 🔗

LDL cholesterol is one of the most widely used prognostic and response biomarkers in cardiovascular medicine. It is both a risk marker – elevated levels predict coronary heart disease – and a pharmacodynamic biomarker: reductions in LDL cholesterol in response to statin therapy confirm that the drug is working as intended. Alongside LDL, high-sensitivity CRP (hs-CRP) is used to assess systemic inflammation. Elevated hs-CRP signals ongoing vascular inflammation and is an independent predictor of cardiovascular events. Brain natriuretic peptide (BNP), released by the heart under increased pressure and volume, is used to monitor heart failure severity and guide treatment adjustments.

HIV: CD4 count as a window into immune health 🔗

In HIV management, the CD4+ T-cell count is the central monitoring biomarker. CD4 cells are the immune cells that HIV targets and destroys, and their count directly reflects the state of a patient’s immune system. Biomarkers like IL-6, D-dimer, and fibrinogen predict cardiovascular disease risk and mortality in HIV-positive individuals, with levels rising significantly when antiretroviral therapy is interrupted. Alongside CD4 counts, viral load measurements – quantifying the amount of HIV RNA in the blood – tell clinicians whether antiretroviral therapy is suppressing the virus effectively. Together, these two biomarkers form the backbone of HIV clinical monitoring worldwide.

Monitoring biomarkers also serve a broader prognostic function by identifying patients at risk of serious complications before those complications develop. There is a subset of biomarkers with substantial scientific evidence that can consistently predict clinical outcomes accurately – making them invaluable tools for clinicians managing complex, long-term conditions.

Diabetes: HbA1c as a long-term glucose indicator 🔗

Hemoglobin A1c (HbA1c) is a key monitoring biomarker for diabetes. It reflects the average blood glucose concentration over the previous two to three months, making it far more informative than a single fasting glucose reading. HbA1c levels can be used to monitor disease progression or the effectiveness of diabetes treatments, and clinical guidelines use specific HbA1c thresholds both to diagnose diabetes and to set treatment targets. A rising HbA1c tells a clinician that current management is insufficient; a declining one confirms that lifestyle changes or medication are working.

Therapeutic development and anti-doping: biomarkers beyond the clinic 🔗

The utility of biomarkers extends well beyond diagnosing and monitoring individual patients. In pharmaceutical research and sports science, biomarkers play a pivotal role in developing new treatments and maintaining the integrity of athletic competition.

Drug development: accelerating therapeutic discovery 🔗

In recent years, biomarkers have become increasingly important in pharmaceutical discovery – identifying a drug’s mechanism of action, investigating toxicity and efficacy signals at an early stage of development, and identifying patients who are likely to respond to therapy. Rather than waiting for clinical endpoints (like disease progression or death) to occur, researchers use biomarker changes as early signals that a drug is having the intended biological effect.

Predictive biomarkers are especially important here. HER2/neu status in breast cancer is a well-known example: women whose tumors overexpress the HER2 protein respond to targeted therapies like trastuzumab, while those who do not overexpress it derive little benefit. This biomarker-guided approach avoids exposing patients to treatments unlikely to help them, reduces unnecessary side effects, and makes clinical trials more efficient. Biomarkers also help identify drug toxicity early – if a liver enzyme rises sharply in patients taking a new drug, that biochemical signal can trigger safety reviews before serious harm occurs.

The promise of personalized medicine is that disease diagnosis and treatment will become faster, cheaper, more accurate, and more effective – and biomarkers are the mechanism through which this promise is being realized. From oncology to neurology to infectious disease, companion diagnostics – tests that identify which patients will respond to a specific therapy – are now a regulatory requirement for many targeted treatments.

Anti-doping in sports: the athlete biological passport 🔗

One of the more novel applications of biomarkers is in competitive sport, where they are used to detect performance-enhancing drug use. Direct doping tests look for prohibited substances or their metabolites in blood or urine. But many doping methods are difficult to detect directly – synthetic EPO used to boost red blood cell production, for example, may clear the body quickly. This has driven the development of an indirect approach: tracking how biomarkers change over time rather than looking for a banned substance itself.

The Athlete Biological Passport (ABP), implemented by the World Anti-Doping Agency (WADA), is built on this principle. The ABP is a longitudinal profiling system of haematological and biochemical biomarkers, combined with calculated scores, analyzed using a Bayesian adaptive model that individualizes reference and cut-off values for each athlete. Rather than comparing an athlete’s results against a fixed population standard, the ABP builds each athlete’s own biological baseline and flags statistically significant deviations from it.

The haematological module of the ABP tracks markers like hemoglobin concentration, reticulocyte percentage, and the OFF-score – a calculated value sensitive to blood manipulation. The steroidal module monitors the testosterone-to-epitestosterone (T/E) ratio and related urinary steroids to detect anabolic steroid use. Because the ABP tracks changes in these biomarkers longitudinally – across months and years of competition – even sophisticated doping practices that avoid triggering a single positive test can be identified through abnormal patterns of change. The ABP is based on the individual and longitudinal monitoring of haematological or urine markers that may be influenced by illicit procedures performed by some athletes, making it a powerful complement to direct substance testing.

The road ahead: challenges and opportunities 🔗

Despite their enormous utility, biomarkers come with important limitations. A single biomarker is rarely sufficient – most conditions require panels of markers interpreted together. Variability in measurement between laboratories, the influence of confounding factors like age, sex, body composition, and altitude, and the high cost of validating new biomarkers for clinical use all slow the translation of promising laboratory discoveries into routine practice. Going from biomarkers to diagnostics used in clinical practice through regulatory affairs remains a key challenge, with thousands of candidate biomarkers identified for various diseases but very few making it into validated, guideline-endorsed tests.

Nonetheless, advances in genomics, proteomics, and metabolomics are rapidly expanding the toolkit. Liquid biopsies – detecting tumor DNA or cancer cells from a simple blood draw – represent the next frontier in cancer diagnosis. Multi-omics panels that simultaneously analyze hundreds of molecular markers using AI-driven interpretation are being developed for conditions ranging from sepsis to Alzheimer’s disease. The integration of biomarker data with imaging, wearable devices, and electronic health records is moving medicine further toward real-time, personalized disease management.

Biomarkers have already transformed how diseases are diagnosed, monitored, treated, and even prevented. Their applications will only deepen as the science matures and costs fall, making precision medicine accessible to more patients and populations worldwide.

What do you think? As biomarker testing becomes more routine – from rapid home tests to comprehensive genomic panels – how should healthcare systems balance the benefits of early, personalized diagnosis against the risks of overdiagnosis and the pressure it places on patients? And with the Athlete Biological Passport already reshaping anti-doping efforts, do you think longitudinal biomarker profiling could eventually replace direct substance testing as the primary tool for enforcing clean sport?

References

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