I remember a patient, Sarah, coming in a while back. She’d been feeling a bit off – tired, a little queasy – and had used one of those at-home urine test strips she’d bought. “It showed ‘moderate’ for ketones in urine,” she said, her voice tight with worry. “What on earth does that mean, Doc?” It’s a common question, and a good one. Let’s talk about it, just you and me.
What are ketones in urine, anyway?
So, ketones. Think of them as little acid compounds your body makes. This happens when your body has to switch gears and use body fat for energy instead of its usual go-to: glucose, or sugar. As your body breaks down fat, ketones are the leftovers, the byproducts of this process.
Like other waste products, your body needs to get rid of these ketones, and one way is through your urine (your pee). When we find ketones in your urine, we call it ketonuria.
Now, here’s the thing: having some, or what we call “trace” ketones, in your urine can be perfectly normal. Your body might need to dip into those fat reserves for energy sometimes. Maybe when you’re sleeping, if you’ve been fasting for a bit, or if you’re following a very low-carbohydrate diet, like the keto diet. No biggie, usually.
But… (there’s always a ‘but’ in medicine, isn’t there?) if those ketone levels get too high, they can actually make your blood too acidic. This is a serious condition called ketoacidosis. It’s a big concern, especially for folks with diabetes, where it’s known as diabetes-related ketoacidosis (DKA). People with ketoacidosis will have high levels of ketones in their blood and usually in their urine too. And DKA? That’s a medical emergency. It needs immediate attention.
How do we check for ketones?
Figuring out if there are ketones in your urine is pretty straightforward. We have a couple of ways:
- At-home tests: You’ve probably seen these. They’re test strips you can buy over-the-counter at most pharmacies. You simply pee into a clean container, dip the strip in, wait a moment for it to change color, and then compare that color to a chart that comes with the kit. The chart usually gives you a range, like “negative,” “trace,” “small,” “moderate,” or “large.” People managing diabetes or those on a strict keto diet often use these.
- Medical tests: In the clinic, we can check for ketones as part of a urinalysis (a general urine test). If we’re worried about ketoacidosis, especially if you have symptoms, we’ll likely do a blood ketone test. This one’s more accurate because it shows the ketone levels in your body right now. Blood tests usually give us an exact number, not just a range.
It’s good to remember that urine tests show what your ketone levels were a few hours ago, since it takes time for your body to make pee. Blood tests give us a more immediate picture.
So, why might this be happening? What causes ketones in urine?
Your body really, really prefers to use glucose from carbohydrates as its main fuel. But sometimes, it’s forced to use fat instead. This switch is what we call ketosis. When your body is in ketosis, it’s breaking down fat and releasing those ketones, which then show up in your urine.
As I mentioned, normal things like sleeping or fasting can cause tiny, trace amounts of ketones in your urine. That’s usually fine. Eating a ketogenic diet, which is very low in carbs, will also definitely put your body into ketosis and lead to ketones in your urine.
But abnormal levels – “small,” “moderate,” or “high” amounts of ketones in your urine – can be a sign of something else going on:
- Diabetes: This is a big one. Everyone needs a hormone called insulin to use glucose for energy. If you have diabetes, your body either doesn’t make enough insulin, or it can’t use it properly. Glucose then builds up in your blood (high blood sugar), and your body has to burn fat for fuel. If this lack of insulin continues, ketones build up, and that can lead to the dangerous diabetes-related ketoacidosis (DKA).
- Alcohol use disorder: Drinking too much alcohol over a long time can mess with how your body absorbs nutrients and stores glucose. This can force your body to burn fat, potentially leading to alcohol-related ketoacidosis. Just like DKA, this is life-threatening.
- Pregnancy: Sometimes, gestational diabetes (diabetes that develops during pregnancy) is the culprit. But really, any of the causes we’re talking about can lead to ketones in urine during pregnancy.
- Prolonged vomiting and/or diarrhea: If you’ve been very sick and losing fluids, your body might run out of glucose and start making ketones.
- Eating disorders and starvation: Conditions like anorexia, or periods of starvation, limit the carbs and glucose available, pushing the body to produce ketones.
- Prolonged, intense exercise: If you push yourself really hard for a long time, you can use up all your stored glucose. Then, your body turns to fat, and yup, ketones can appear.
“Can I have ketones in my urine if I don’t have diabetes?” I get asked this. Yes, you absolutely can have those trace or small levels. But if you don’t have diabetes and you’re seeing moderate or large amounts of ketones? That’s not typical. You should get checked out right away – call 911 or go to the nearest emergency room. It could be undiagnosed diabetes or another serious issue.
What do these levels mean? Interpreting the results
Okay, so what’s considered “normal” for ketones in urine?
For most people, seeing “trace” or “small” levels of ketones is generally okay and nothing to panic about.
But if you have diabetes or another condition that puts you at risk for ketoacidosis, even these lower levels can be a heads-up, depending on the situation. For example, if your blood sugar is high (say, over 250 mg/dL) and you see even trace ketones, it’s wise to keep a close eye on your blood sugar and recheck your urine for ketones to make sure they aren’t increasing.
What’s a dangerous level of ketones in urine for someone with diabetes?
Honestly, any level of ketones above “small” or “trace” can be a worry, especially if you’re at risk of ketoacidosis.
- A small amount of ketones in your urine means your risk of ketoacidosis is going up. If you have diabetes, this is the time to call your doctor or diabetes care team for advice on what to do.
- A moderate or large amount of ketones? That means you’re at serious risk of ketoacidosis. Please, don’t wait. Head to the nearest hospital for medical treatment.
And what about “trace ketones in urine“? If you don’t have diabetes, a “trace” level is usually fine. Most of us have these tiny amounts from time to time.
How would I even know? Symptoms to watch for.
Yes, if you have ketones in your urine, you might notice other things too, depending on how high the levels are.
Symptoms of Ketosis (usually small amounts of ketones)
When your body is in ketosis (which often leads to those small amounts of ketones in your urine), you might feel:
- A bit of an upset stomach
- Headache
- Tiredness
- Some brain fog – just not feeling sharp
- That “keto breath” – a distinct, sometimes fruity or metallic smell
- Constipation
- Trouble sleeping (insomnia)
Symptoms of Ketoacidosis (moderate to high amounts of ketones)
This is the serious one. Moderate to high amounts of ketones in your urine could mean you’re developing ketoacidosis – either DKA or alcohol-related ketoacidosis.
Early signs of DKA might include:
- Peeing a lot more than usual (frequent urination)
- Feeling incredibly thirsty (polydipsia)
- Feeling super hungry (polyphagia)
- Signs of dehydration (dry mouth, dark urine)
- Headache
If it gets more severe, or if it’s alcohol-related ketoacidosis, the symptoms can ramp up:
- Nausea and vomiting
- Abdominal pain
- Diarrhea
- Shortness of breath or a specific type of deep, rapid breathing called Kussmaul breathing
- A fruity smell to your breath
- Feeling extremely tired or weak
- Feeling disoriented, agitated, or confused (altered mental status)
- Decreased alertness, or even passing out
If you or someone you know has these more severe symptoms, please, it’s crucial to get medical help immediately.
Take-Home Message: What to Remember About Ketones in Urine
Alright, let’s boil this down to the key points:
- Ketones in urine (ketonuria) happen when your body burns fat for energy instead of sugar.
- Trace or small amounts of ketones can be normal, especially with fasting, sleep, or low-carb diets.
- High levels of ketones can lead to ketoacidosis, a serious condition requiring urgent medical care, especially diabetes-related ketoacidosis (DKA).
- You can test for ketones in urine at home with strips or through medical tests like a urinalysis.
- If you have diabetes and find moderate to large ketones in your urine, seek medical help right away.
- Symptoms like fruity breath, extreme thirst, frequent urination, nausea, and confusion alongside ketones in urine are red flags.
It can be a bit unsettling to see something unusual on a test strip, I know. But understanding what ketones in urine mean is the first step to managing your health. We’re here to help you figure it out. You’re not alone in this.