8-Hydroxy-2-deoxyguanosine Test

Every cell in your body is running a constant cleanup operation against unstable oxygen molecules created by normal metabolism. When those molecules hit DNA before your repair systems catch them, they leave a specific chemical fingerprint called 8-OHdG (8-hydroxy-2-deoxyguanosine). Your body cuts the damaged piece out and sends it into the urine, where it can be measured.

This urine test gives you a window into how much oxidative damage your DNA is taking right now and how well your repair machinery is keeping up. It is a research-grade marker rather than a guideline-recommended test, but levels run higher in people with diabetes, cardiovascular disease, kidney disease, several cancers, and heavy smokers, and they shift with lifestyle and certain medications.

What 8-OHdG Actually Reflects

8-OHdG is an oxidized form of one of the four letters in DNA (the letter G, or guanine). When unstable oxygen molecules attack DNA, a specific repair enzyme cuts out the damaged piece, which then travels through the blood and exits in urine. The amount you excrete reflects the running balance between damage and repair across your whole body.

Higher levels generally mean more oxidative DNA injury, less efficient repair, or both. Because nearly every chronic disease tied to aging involves some component of oxidative stress, this single marker shows up as elevated across a long list of conditions, from coronary artery disease to depression. That breadth is both its strength and its limitation: it tells you something is straining the system, but not exactly where.

Heart Disease Risk

A systematic review and meta-analysis found that people with cardiovascular disease consistently have higher 8-OHdG in both urine and blood than people without it. Heart failure follows the same pattern, with levels rising step-by-step as symptoms worsen (NYHA class), suggesting the marker tracks the underlying stress on the heart muscle.

In chronic systolic heart failure, urinary 8-OHdG predicted cardiac events and tracked the effect of carvedilol (a beta-blocker) on disease progression. In active cardiac sarcoidosis, a urinary cutoff of 17.5 ng/mg creatinine flagged ventricular tachycardia with 89% sensitivity and 83% specificity, and a cutoff of 19.1 ng/mg creatinine predicted cardiovascular-related death better than BNP, a standard heart-failure blood test.

Atrial Fibrillation

Blood 8-OHdG rises with more advanced atrial fibrillation, predicts which people will have a recurrence after treatment, and correlates with scarring in the upper chambers of the heart (atrial fibrosis). One study of 384 people found that higher plasma levels marked more advanced fibrosis stages, with DNA methylation genes influencing how high those levels run in any given person.

Type 2 Diabetes and Coronary Artery Disease

In a study of 2,621 people with type 2 diabetes, higher 8-OHdG inside the energy compartments of white blood cells (mitochondrial DNA) was independently linked to having blocked coronary arteries, the severity of the blockages, inflammation as measured by CRP, and adverse events over the following year. This relationship held up after controlling for the usual diabetes and cardiovascular risk factors.

Kidney Disease

In type 1 diabetes, a study of 1,623 people found that those in the top third of plasma 8-OHdG had roughly three times the risk of progressing to end-stage kidney failure compared with those in the lowest third, along with more protein in the urine (albuminuria) and lower filtration rates. In type 2 diabetes, serum 8-OHdG ran higher in people with diabetic kidney disease, independent of other risk factors.

In chronic kidney disease more broadly, a study of 376 people found that higher serum 8-OHdG was associated with increased death from any cause, and this association held up even after accounting for inflammation. That last point matters because most kidney biomarkers track inflammation closely; 8-OHdG appears to capture something additional.

Cancer Associations

Urinary 8-OHdG runs higher in people with colorectal cancer than in matched controls, with levels rising in those with metastatic disease. In prostate cancer, urinary levels normalize after surgical removal of the tumor, suggesting the marker tracks tumor burden. Similar patterns appear in gastric carcinoma, with levels falling toward normal after the tumor is resected.

In non-small-cell lung cancer, high 8-OHdG in tumor DNA was associated with roughly three times the risk of death compared with low levels in resected patients. Oral squamous cell carcinoma shows strong 8-OHdG staining linked to larger tumors and worse survival.

Cognitive and Mood Disorders

A meta-analysis comparing mood states in bipolar disorder found that peripheral 8-OHdG runs higher specifically during depressive episodes, not during mania or euthymia, with older age and female sex amplifying the effect. In a cross-sectional study of 1,312 elderly adults, higher plasma 8-OHdG was associated with motoric cognitive risk, a pattern that may precede dementia.

Reference Ranges

There is no consensus clinical cutpoint for 8-OHdG. The numbers below come from a systematic review and meta-analysis that pooled urinary measurements from healthy adults across many studies, mostly using mass spectrometry methods, and are best treated as orientation rather than a target. Your lab will likely report different numbers, possibly in different units.

Source: Graille et al., 2020 meta-analysis of urinary 8-OHdG. Compare your results within the same lab over time for the most meaningful trend, since values vary by method (mass spectrometry typically gives lower numbers than ELISA-based kits).

When Results Can Be Misleading

This marker has substantial day-to-day and within-person variability, and several factors can push a single reading in misleading directions:

• Recent intense exercise: tissue 8-OHdG can rise 22% immediately and 66% by 24 hours after resistance exercise, normalizing within days. Sample at least 2 to 3 days after a hard workout.
• Acute illness or infection: inflammatory states like COPD exacerbation or acute heart failure spike levels temporarily, which can mimic chronic disease.
• Urine dilution: spot urine results depend heavily on how much water you drank; creatinine normalization helps but does not fully correct this.
• Air pollution and chemical exposures: short-term exposure to particulate matter or polycyclic aromatic hydrocarbons (a class of pollutants from combustion) raises urinary 8-OHdG by roughly 6 to 7% per typical exposure increment over the prior days.

Why One Reading Is Not Enough

Oxidative stress is dynamic. Diet, sleep, training load, illness, and pollution all shift levels over hours to days, so any single measurement captures a snapshot rather than your baseline. The way to extract real signal is to track the trend over time, ideally collecting samples under similar conditions (same time of day, similar hydration, no intense exercise in the previous 48 hours, no acute illness).

A reasonable cadence: establish a baseline now, retest in 3 to 6 months if you are making meaningful lifestyle changes or starting a new medication that may affect oxidative stress, then at least annually thereafter. Consistent direction across multiple readings means more than any single number.

What to Do If Your Result Is High

Because 8-OHdG reflects a general oxidative burden rather than a specific disease, an elevated result is a prompt to look at companion tests that point to which system is under strain. If you have not already, check fasting glucose, HbA1c, and a lipid panel for metabolic stress; hs-CRP for systemic inflammation; eGFR and urine albumin-to-creatinine ratio for kidney involvement; and ApoB and Lp(a) for cardiovascular risk.

Persistent elevation alongside abnormal results in any of those panels is worth discussing with a physician who specializes in the affected system, whether that is a cardiologist, nephrologist, or endocrinologist. If your other markers look clean and you have controllable inputs driving the result (smoking, heavy pollution exposure, sleep deprivation, alcohol), addressing those and retesting in a few months gives you a clearer signal.