Scientists Just Developed a Urine Test That Reveals Your True Biological Age

How old are you really? The answer is in your pee.

For years, the “gold standard” for measuring biological age — which is how fast you’re aging, regardless of what your birthday cake says — has been DNA methylation clocks. These tests are accurate. But they are also expensive, time-consuming, and usually require someone to stick a needle in your arm.

A breakthrough study published in npj Aging just introduced a refreshing alternative: a urinary microRNA aging clock. By analyzing microscopic “bubbles” in urine, researchers achieved a level of precision comparable to invasive blood tests without the needle.

How It Works

The study utilized a machine learning system called LightGBM, trained on a cohort of 6,331 Japanese adults. Its job was to interpret the complex patterns of urinary microRNAs.

Think of microRNAs as tiny data packets. They travel inside microscopic bubbles (technically called extracellular vesicles) and carry crucial information about your body’s internal state. The problem is that untangling this information is far from straightforward. That is where the AI comes in. By associating these complex chemical patterns with known biological ages, the system learned to recognize how old a new patient is biologically.

To make sure they weren’t just seeing statistical noise, the researchers validated the results against known aging markers. For example, they tracked specific microRNAs like miR-34a-5p and miR-31-5p. These are known to spike when cells stop dividing and grow old. When the researchers saw these levels rising in the urine samples, they knew they had captured a valid biological signal.

The model achieved a Mean Absolute Error (MAE) of roughly 4.4 years. While that is slightly less precise than the DNA methylation blood test, it outperforms other blood-based RNA clocks. More importantly, it is completely painless and scalable.

Why Does This Matter?

Knowing your biological age, and factors that can accelerate or slow it down, can be an important part of your lifestyle. Your chronological age is just a number. Your biological age is a prediction of your health.

For instance, the researchers found that for people with Type 2 diabetes, the clock runs faster. Specifically, men and women with diabetes showed an elevated “Delta Age” — the gap between how old they are and how old their body acts. This suggests diabetes could put people at increased risk for other age-related problems, which could warrant more aggressive diabetes interventions.

Or you could, perhaps, infer certain problems. Imagine a world where a simple urine test during your annual physical could flag that you are aging too fast, years before a chronic disease sets in. The study even detected microRNAs linked to Alzheimer’s and dementia, hinting that this method could eventually help screen for brain health, though more research is needed there.

This technology isn’t perfect yet. The study authors note that the clock gets a bit fuzzy at the extremes — it struggles to be as accurate for people under 25 or over 80. Hydration also plays a role. How much water you drink changes the concentration of your urine, which can complicate the analysis, though the team developed quality control steps to manage this.

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But the trajectory is promising.

The Future of Testing is Yellow

We are moving toward a future of personalized, preventive medicine that is scalable and accessible. Blood draws require clinics, phlebotomists, and cold chains. Urine collection requires a cup and a bathroom.

This study joins a growing body of work that has successfully leveraged urine to detect early-stage health issues, including ovarian, esophageal, and pancreatic cancers. These urine tests are already comparable or even outperform blood tests in sensitivity.

While those studies focused on hunting down specific diseases or monitoring local kidney function, this new aging clock broadens the scope significantly by proving that urine can also capture a systemic measurement of overall biological decline. By turning a waste product into a window into our cellular health, we might finally be able to stop watching the clock and start slowing it down.

Journal Reference: Milos Havelka et al, A urinary microRNA aging clock accurately predicts biological age, npj Aging (2025). DOI: 10.1038/s41514-025-00311-3