Can bladder biometrics tell me if my kidneys are healthy?

It can show you one meaningful piece, not the whole picture. Measuring your urine output reflects part of what your kidneys are doing, but a complete kidney assessment needs bloodwork, specifically a creatinine level, which is used to estimate your GFR (glomerular filtration rate). GFR is my favorite number in all of medicine, because it's the single best snapshot of how well your kidneys are filtering. Bladder biometrics can't measure GFR, and nothing you do at home can. What it can do is get you paying attention to your urinary system early, so that if you ever do get bloodwork, you're walking in already curious and informed instead of blank.

Is this about kidney health?

Yes, more than people realize. Here's the relationship: your kidneys make the urine, and your bladder just holds and reports it. The bladder is the messenger. When you measure your output over a few days, you're collecting the messages and adding them up, and that tells you something real about what your kidneys are doing, especially how much they're producing and how that changes between day and night. It's not the whole kidney story, but it's a genuine window most healthy people never get to look through.

What do the kidneys actually do?

More than most people give them credit for. They filter your blood, balance your fluids and electrolytes, manage blood pressure behind the scenes, and decide how much water to keep versus send out as urine. That last job is the one you can actually observe at home. How much your kidneys choose to excrete, and when, is information, and it shows up in your output.

What is GFR, and what is a normal GFR?

GFR stands for glomerular filtration rate, and it's the number doctors use to grade how well your kidneys are filtering your blood. It requires a blood test, not urine, so it lives in the doctor's office. A GFR of 90 or above is generally considered normal. Here's the part I care about and plan to talk a lot about: the range from 60 to 89 often gets labeled "normal" or waved off, but it can represent mildly reduced filtration. Kidney decline happens on a long, silent runway. It doesn't announce itself, which is exactly why paying attention early matters. Most healthy people have never heard of the single most important measure of their kidney function. That gap is a big part of why this project exists.

How is this different from a bladder diary or tracker app?

A diary records events. You went, you wrote it down, and you are often guessing about the volume. Bladder biometrics uses real measurement and your whole fluid picture, intake and output together, and turns it into numbers you can actually compare. The measuring is what makes it biometrics instead of a log.

Do I have to have a problem to do this?

No. The opposite is true. This was built for healthy people with generally healthy bladders first. Establishing your baseline and patterns while everything feels fine is arguably the best time to do it, you can't know what's changed if you never knew your normal. A person doing BB might have mild bladder signals or questions about urinary health but nothing feels major. This is for you as well!

Is this just for women or old people?

No. And I hope to change that part of the conversation. Bladders and kidneys are standard operating equipment. Urinary health gets coded as a women's issue, an elderly issue, or a pregnancy issue, and that coding is exactly what leaves everyone else without information. This is for all ages and all genders. It's a they all day for bladder pronouns.

How long does it take?

The best length is 3 days, and it can be done over separate days. While 1 day is totally worth it, adding a couple of extra days smooths out an off day in your data. It's a short, finite body exploration and very similar to wearing and tracking your glucose for a few days as a non diabetic. You stop in and do BB, learn and move on. In fact, try it with CGM at the same time, you're already tracking meals, why not?

Do I have to do this forever?

No. You run it, you learn your normal and patterns of interest, and you put it down. Repeating it once a year is plenty for most people, that's what I do.

Is this a diagnostic tool?

Bladder biometrics is just like wearable data or a continuous glucose monitor for an individual without diabetes. It functions to surface patterns, show baselines and allow a person, if curious, to see how it connects to other data like sleep, glucose and HRV. Any diagnostic tool in medicine must be paired with a physical exam and reconciled with your full medical history. No wearable or home monitoring or form of measurement can therefore be a diagnostic tool and that includes bladder biometrics methodology.

Why measure? Can't I just estimate?

Estimating flattens the story. A number is honest in a way a feeling isn't. If you suspect a fever, you use a thermometer, a hand on the forehead is decent, but it isn't the same. The bladder is no different. I'm an expert and my own guesses (because yes, I tried out the guess method) were off by about 100-150 cc.

What do I need to measure?

A simple measuring tool with clear markings. That's it. They're inexpensive, widely available, and easy to read. There is a kit I sell and even a digital guide. But the equipment is not hard to come by, a strength of this biometric.

Why not use an app that estimates volume from sound?

Some tracking beats none, so if that helps you, use it. But acoustic estimation needs a quiet environment to work well. And after years in the urology lab, I prefer measurement for an accurate assessment. And you're already standing right there at the source, if you're that close, measuring is simpler than estimating. During the biometrics, it allows you to engage more with what the volume actually looks like as well as true color. With sound it's gone and diluted in the toilet.

Do I need to buy your kit?

No. The method of truly measuring matters way more than the container. Bladder health shouldn't be gatekept behind a purchase. The digital guidance and support might be helpful if you want more than a list of normal values and a bit more depth for your health portfolio.

Isn't measuring urine kind of gross?

I'm biased but I don't think so. It's just a liquid and just simply rinse the container and wash your hands like normal. You're doing it at home, in private, for a short period of time. Most people find it much easier than it seems, and the payoff is data nobody has ever handed them before. It's easier than a needle poke for wearing a CGM monitor in my opinion, and just as useful.

What if I'm at work or traveling during my capture?

Pick days when you aren't traveling for a result that is more accurate and measurable.

Are there any limitations?

Just one and this applies to every app and direct to consumer products. At home, you can only measure output. Total bladder capacity equals the amount that comes out plus the amount left behind in the bladder. It is normal to leave up to 100 cc in the bladder, and just like a blood pressure, the effectiveness of your bladder pump can vary with stress/HRV and amount of fluid in the bladder to name a few. Measuring methods like before and after weights, sound tech and a graduated cylinder tool all measure output. But, for a well person with a generally healthy bladder, this number should not be elevated. If you have concerns about emptying, that is always best answered in the doctor's office. An experience like bladder biometrics can still help you see a pattern like this but does not substitute for medical attention and is not a diagnostic tool.

If I do it at home and my days at work are different, how does it help?

I have had this question too many times to count. And it's a good one. The answer is it 100% still helps. By knowing and logging your home numbers, it sets a baseline. It is still your foundation. Then, if you can identify 1-3 things that are different at work, you can more accurately understand them even without measurement. You might find out you drink more because there is a drinking fountain near your desk. You might notice that your output volumes are lower because your ear gets trained when you measure for a couple of days at home. It's much easier to trouble shoot a pattern at work or traveling once you know your home base. I promise you, that is the feedback I heard for years.

How is this different from products that measure my flow rate?

Products that measure flow are inherently connected to those who think they may have a bladder emptying issue. For that reason, those apps are often connected to a doctor's prescription and often, to a urologist's office. They are often associated with and designed for individuals with certain urologic conditions that affect bladder health like enlarged prostate or other conditions that cause the bladder emptying to break down. If a person has a serious concern about bladder emptying and how fast their flow is, that cannot be addressed with a flow rate product alone, which is why they connect to a doctor's office. Bladder biometrics and related tools and resources are designed for healthy people with generally normal bladders or who may have some mild or medium signals. It is not connected to a doctor prescription or a medical office. However, just like other wearable or home monitoring data, you can take it to your doctor if you would like.

What will my numbers actually tell me?

Broadly: whether your intake and output are in balance, how much your bladder holds before it signals, and how your body shifts kidney output production between day and night. Those shifts can reflect metabolism, hydration and sleep quality.

What's a "normal" number of times to go pee per day? How often is too often?

There's a typical range, and there's your range, and the second one is the point. Population numbers give context; your own baseline is the actual tool to figure out where you stand. And it's relative. If you are drinking normal amounts of fluid like 65-70 oz/day, you would likely go around 7 times a day. However, if you are committed to very high levels of fluid intake for any reason, it will be necessary to use the bathroom more frequently. Without measurement of intake and output, it's all just a guess, which is why this method is best for answering the question accurately.

Why do I wake up at night to pee?

Night waking has more causes than most people expect. The default is to blame the bladder but it’s often just the messenger. Factors such as fluid timing, amount or type consumed, sleep quality, and your overnight glucose levels are all potential culprits. Meaning, your bladder is innocent! Bladder biometrics is a fair process that helps surface patterns and even root causes. Measuring your day against your night output lets you use your own data vs just guessing.

Is it normal to feel urgency after coffee?

Very common, and usually more about the coffee than the bladder. Caffeine is a diuretic which means, for a period of time, you will make pee very quickly. And it’s a mild bladder irritant. Therefore, a little urgency after your morning cup can be your bladder responding to what you drank. Measuring helps you see if the urgency or pressure you feel makes sense and how it times with your cup of coffee.

Why do diuretics like alcohol, caffeine and medication cause me to pee so much?

Good one! Alcohol and caffeine cause you to physically make more urine for a few hours. If a person takes birth control, it can keep caffeine in your system for up to 12 hours! So the increased pee is real because you literally make more. This is because you release more water into the urine and it can even look more dilute. But there’s another reason. Making urine rapidly triggers the bladder to contract and that’s called a bladder spasm. It is well documented in urinary literature. And it happens to normal people of all ages! So if you are hard core hydrating or if you are drinking diuretic fluids like alcohol or caffeine the fast rate of fluid build up can create a drive to pee that is simply because the bladder is getting overloaded and “triggering.” By logging what you drink, you get to observe if there is a correlation to how your bladder feels.

How much should I be drinking? How much water per day is normal?

More individual than most advice admits. It depends on your size, your activity, your climate, and your medical history. The reference points are in the wellness guide, but around 65-70 oz is normal and healthy for most people. More is not automatically better. Going over this amount can add strain to the bladder and requires more attention to bathroom habits.

What color should my pee be? Is clear urine healthy?

Pale yellow is normal and healthy. Chasing clear urine is one of the more common mistakes I see, and it usually means someone is overdoing fluids. Clear isn't a gold star. It can be a sign you've pushed water past what your body needed. Color is also a rough signal at best, because so many things shift it: vitamins, food, medications, and how long since you last went. It tells you very little about your actual output, and nothing about your day-versus-night pattern. If you want to more deeply understand what’s going in and coming out, measurement is the key. As for why your urine is a certain color, that’s where a urinalysis is helpful–but that’s a doctor visit or buying home urine strips.

Why is my pee dark yellow in the morning?

That first morning pee is usually your most concentrated of the day, and that's normal. You didn't drink anything for eight hours, so it's expected to be darker. It's not a signal to start slamming water the moment you wake up. Morning concentration is one of the clearest examples of why a single glance at color, without context, misleads people.

Can I pair this with my other wearables?

That's the best use of it. Bladder data next to your glucose, sleep, and HRV starts a conversation between your numbers that none of them can have alone. Overnight fluid shifts alongside overnight glucose is a particularly interesting pairing. Of these data points, the most actionable are bladder and glucose. And optimizing both informs sleep.

Is this medical advice? Is it a diagnosis?

No. This is education and normal body tracking like your wearable, glucose monitor, thermometer or home blood pressure cuff. Bladder biometrics is another form of measurement. And like your other data, it can be shared with your physician.

What if I see something that concerns me?

All wearables and home testing or monitors can surface questions. That is why people take wearable and other information available to their doctor if something surfaces. Regardless of whether you use a wearable, thermometer, blood pressure checker or bladder biometrics, take it to your doctor. Walking into an appointment with a few days of real data is a meaningfully different conversation than walking in with a description by itself. It adds depth to your medical visit.

I already see a urologist. Is this still useful?

Yes. Understanding your own patterns doesn't compete with your care, it informs it. Plenty of people find that having their own data makes their appointments more productive. Your urologist will be blown away if you arrive with this kind of data!

What are the three bladder types?

I introduced this classification to include people with healthy bladders. It is not a diagnosis–just a way to think about your own situation. Type 1 might not think about their bladder other than what’s necessary, and is simply curious or loves biohacking. Type 2 notices the occasional thing and wonders if it's normal or maybe has a few signals–nothing severe. Type 3 is dealing with identifiable issues, might have a diagnosis and is likely seeing a doctor already. All three can use the same tool for different reasons. A person who self-identifies as a type 3 may not have ever been offered this kind of home system.

Which type am I?

There is a description of the 3 bladder types on the home page. See which one fits you. The 3 bladder types are not a diagnosis, I use this classification to ensure inclusion of healthy people and self-select where they identify. It's a self-directed assessment of how YOU see yourself and your overall urinary health. I love the classification because it prioritizes how you view your own health. Us doctors have plenty of labels; so this one is for you to decide on.

Is my information private?

Yes. See our Privacy Policy for how your information is handled. If you use the app, it is self hosted which means, no one but you has the data.

Do I need the BB app?

No. You can capture your data with old fashioned paper, pencil and a measuring tool. The app makes the logging and the math easier, and it keeps your results in one place.

I'm Dr. Mia Duncan, dual board-certified in urology and urogynecology. I spent years doing advanced urologic testing and operating on bladders that got bad quietly, over years, while nobody was looking or where things were normalized. It creates what feels like a cliff, where one day the bladder is blamed for going bad. As if one day, the bladder went rogue or something. But the urinary health changes are a slow burn over time and it's easy to put the fire out early when you are already acquainted with the bladder and kidneys. I made this because there was nothing out there for healthy people and their urinary tracts. Care is locked behind the surgical doors of urology and to enter nephrology, the medical side of urinary health, you are referred if you have "kidney disease" of some variety. There was clearly no place for healthy people to go and while we have the ability to cheaply measure aspects of bladder and kidneys at home, no one is talking about it.

Thus, I built this for healthy people because it's important to avoid gate keeping any aspect of our health around age, gender or being "sick enough." Join me in starting the conversation about urinary health and connecting with your own early and often. Conversations about and attention to your urinary health early and often will pay dividends.