By Dr. Muhammad Awais Rabbani, MBBS · Medically reviewed by Dr. Ahmed Humayon, MBBS · Updated 28 October 2026 · Editorial policy
Ketones in urine mean your body is burning fat for fuel instead of sugar. Trace or small amounts are common after fasting, vomiting or a low-carb diet; moderate or large amounts with diabetes need action today.
Diabetes, ketones and vomiting, heavy breathing or confusion? Call 911 or go to the ER now.
Check your ketone result
Urine ketone result checker
This tool does not diagnose. If you feel very unwell, call 911.
A dangerous level of ketones in urine depends on who you are. With diabetes, moderate or large ketones mean calling your diabetes care team right away, and any ketones with vomiting, heavy breathing or confusion mean the ER (ADA; MSKCC). A healthy adult who is fasting or eating keto and feels well can expect a positive strip.
The urine ketone result checker uses the Ketostix color chart (Ascensia), the American Diabetes Association’s ketone guidance and Memorial Sloan Kettering’s patient instructions. Tool thresholds reviewed by Dr. Ahmed Humayon, MBBS. This tool does not diagnose. If you feel very unwell, call 911.
What do ketones in urine mean?
Ketones in urine, called ketonuria, mean your body is short of usable sugar and has switched to burning fat. When your body breaks down fat, the liver turns it into ketones, which spill into urine as blood levels rise. A trace can follow an overnight fast; large amounts with diabetes can signal an emergency.
There are three ketone bodies, and they behave differently on a test. Acetoacetate is the one a urine strip detects. Beta-hydroxybutyrate is the main ketone in the blood, and the nitroprusside reaction on a strip does not measure it (Rodriguez Alvarez et al., CCJM 2025). Acetone, the third, leaves through the breath. Heart, muscle and brain can all run on ketones when glucose is scarce, so low amounts during fasting are normal physiology.
Ketones build up when insulin is too low to move sugar into cells, or when you eat very few carbohydrates.
Ketone levels in urine: trace to large, and what your lab report shows
A normal urine test shows no ketones and reads negative. Home strips grade urine ketones as trace, small, moderate or large, which on the Ketostix chart equal 5, 15, 40 and 80 to 160 mg/dL. A higher grade means more ketones in the sample. What a grade means for you depends on diabetes, pregnancy and symptoms.
| Strip grade | Urine (mg/dL) | What it usually means |
|---|---|---|
| Negative | 0 | No ketones detected |
| Trace | 5 | Common after fasting or hard exercise. With diabetes, recheck in 2 to 4 hours (ADA) |
| Small | 15 | Same as trace if you feel well. With diabetes, recheck in 2 to 4 hours (ADA) |
| Moderate | 40 | With diabetes, call your diabetes care team right away (MSKCC) |
| Large | 80–160 | With diabetes, call now; go to the ER if you can’t reach them (ADA) |
Values from the Ketostix reagent strip insert (Ascensia Diabetes Care). Other brands print their own chart.
Urine strips report mg/dL. Blood meters report mmol/L and measure a different ketone, so a strip grade has no exact mmol/L equivalent. Labs that print 1+ to 4+ set their own scale; read the word or the mg/dL value printed beside it.
Reading the ketone line on your lab report
On a lab report, the same test can appear as KET, U-ketone, Ketones UA, Ketones UR or POCT ketones. UA stands for urinalysis, UR for urine, and POCT means point-of-care testing, usually a dipstick read in the clinic. The word negative printed beside your result is the lab’s reference interval, the result expected in healthy people, so even a trace gets flagged as abnormal.
Ketones are one line on a longer report. Our guide to reading creatinine on the same lab report covers another.
Is trace ketones in urine normal?
A trace of ketones in urine is common and usually harmless in someone without diabetes. The Ketostix maker lists fasting, pregnancy and frequent strenuous exercise as everyday reasons for detectable ketones. In diabetes, any positive reading calls for a recheck in 2 to 4 hours (ADA).
Common reasons for a trace result without diabetes:
- First-morning urine after a night without food
- Concentrated urine, shown as a high specific gravity on the same report, which packs the same ketones into less water
- Vomiting, diarrhea or a day of eating very little
If trace ketones keep showing up with no clear reason, raise it at your next appointment.
When are ketones in urine dangerous? Warning signs and when to go to the ER
Ketones in urine are dangerous when they come with diabetes and either a moderate or large reading or symptoms such as vomiting, belly pain or heavy breathing. That combination can mean diabetic ketoacidosis (DKA), a life-threatening condition in which high ketone levels make the blood acidic. The ADA calls it an emergency that needs urgent medical care.
Call 911 or go to the ER if you have ketones and any of these (ADA):
- Vomiting or trouble drinking
- Heavy or rapid breathing
- Confusion or feeling very tired
- Ketones that stay high or get worse
- You can’t reach your doctor
Other DKA symptoms the ADA lists are nausea, abdominal pain and fruity-smelling breath.
High ketones can also appear when blood sugar looks normal. Euglycemic DKA has become more common since SGLT2 inhibitors, diabetes medicines that make the kidneys pass sugar into urine, came into use (Rodriguez Alvarez et al., CCJM 2025). If you take an SGLT2 inhibitor and are not eating or drinking normally, test for ketones even when blood glucose is under 250 mg/dL (MSKCC).
People with diabetes who use insulin usually have sick-day rules from their care team. Follow them first. The ADA says to keep taking insulin as directed and never to stop it unless your doctor says so.
How to test for ketones in urine at home
To test for ketones in urine at home, dip a ketone test strip into a fresh urine sample, read it at the exact time on the label, and match the pad to the color chart on the bottle. Strips are sold over the counter, and the whole check takes under a minute with no lab visit.
- Check the date. Expired strips may read low, and a Ketostix bottle is good for six months after you first open it.
- Collect urine in a clean, dry cup, or pass the strip through the stream.
- Dip the pad briefly and tap off extra urine on the rim.
- For Ketostix, read at exactly 15 seconds and ignore color changes after that. Other brands differ, so follow your label.
- Hold the strip beside the chart in good light and pick the closest match.
- Write down the result, the time and, if you have diabetes, your blood sugar.
If you have diabetes, the ADA advises checking ketones when you feel unwell, when blood glucose stays at 250 mg/dL or higher for 2 hours, or when you are sick, dehydrated or fasting. A first-morning urine sample often shows a trace from the overnight fast.
Urine vs blood ketone test: which is more accurate?
A blood ketone test is more accurate than a urine test for deciding what to do right now. A blood ketone meter measures beta-hydroxybutyrate in mmol/L, and the 2024 adult consensus on hyperglycemic crises prefers that measurement at diagnosis and during treatment. The ADA also names the blood meter as the most accurate home option.
| Urine test strip | Blood ketone meter | |
|---|---|---|
| Measures | Acetoacetate | Beta-hydroxybutyrate |
| Unit | mg/dL, or trace to large | mmol/L |
| Early in DKA | Can read lower than the true level | Shows the current level |
| During recovery | Can stay positive after blood ketones fall | Falls as you improve |
| Best for | Screening, fasting, keto | Diabetes with illness, unclear strip results |
Strips use a nitroprusside reaction that turns the pad purple when acetoacetate is present. Because of that chemistry, a urine reading can mislead in both directions. It can underestimate ketosis when DKA starts, and during recovery it lags behind blood ketones, staying positive after they fall (Rodriguez Alvarez et al., CCJM 2025). A false negative is a strip that reads low while beta-hydroxybutyrate is climbing. A false positive can come from captopril or valproic acid (CCJM), from mesna, levodopa metabolites or highly pigmented urine (Ketostix insert), and on some strips from blood in the sample (FDA 510(k) K170587).
In a blood test, a beta-hydroxybutyrate of 3.0 mmol/L or more is one of the three criteria for DKA in the 2024 consensus.
If your strip and your symptoms disagree, trust the symptoms and use a blood meter or get a blood test.
What do ketones in urine look like?
Ketones in urine have no color you can see. Urine that contains them can look normal, darker if you are dehydrated, or foamy if protein is also present. Only a test strip shows them, with the pad shifting from beige toward dark purple as levels rise.
Ketones with protein, blood, glucose or a UTI
A second finding on the same urine test changes what ketones point to. Ketones with glucose suggest blood sugar high enough to spill into urine, which needs a same-day check if you have diabetes. Ketones with protein often follow fever, hard exercise or dehydration. Ketones with leukocytes or nitrites can mean a UTI that has stopped you eating or drinking well.
| Combination | What it usually points to | What to do |
|---|---|---|
| Ketones + glucose | Blood sugar high enough to spill into urine | Check blood sugar today; urgent if you have diabetes and feel sick |
| Ketones + protein | Fever, intense exercise or dehydration; sometimes kidney stress | Repeat the test once you are well; persistent protein needs a doctor |
| Ketones + blood | Exercise, menstrual contamination, stones or infection; on some strips, blood itself reads as ketones | Repeat when not menstruating; see a doctor if blood persists |
| Ketones + leukocytes or nitrites | Possible UTI with poor intake | See a doctor for a urine culture and treatment |
A UTI raises ketones indirectly, through fever, nausea and poor appetite, which is why the two often share a report.
What causes ketones in urine?
Ketones appear in urine whenever your body runs short of usable glucose and burns fat instead. That happens when insulin is too low, as in uncontrolled diabetes, or when too few carbohydrates come in through fasting, vomiting, illness or a strict low-carbohydrate diet.
- Not enough insulin: missed doses, an insulin pump that leaks at the infusion site, or diabetes that hasn’t been diagnosed yet
- Illness, fever or vomiting, which cut how much you eat
- Fasting, skipping meals or frequent strenuous exercise
- A keto diet or other low-carb plan, where ketones are the goal of a ketogenic diet and a positive strip is expected
- Heavy drinking or alcohol use disorder, which can lead to alcoholic ketoacidosis
- Pregnancy; with severe vomiting, urine ketones help doctors judge how serious hyperemesis gravidarum is (MSD Manual)
Dehydration mostly works by concentrating urine, so any ketones present read darker. The vomiting or poor intake behind most dehydration raises ketones as well, and the ADA lists dehydration as a reason to check them. Fluids plus food usually fix both in someone without diabetes.
How to get rid of ketones in urine
How you get rid of ketones in urine depends on why they are there. Without diabetes, eating carbohydrates and drinking fluids usually clears small amounts. With diabetes, ketones often mean your body needs more insulin, so follow your care plan and call your healthcare provider.
Without diabetes, eat a normal meal with carbohydrates, sip fluids, and recheck the next morning.
With diabetes, the ADA’s steps are to keep taking insulin as directed, drink plenty of water or sugar-free fluids, take correction insulin if it is part of your plan, check your pump and infusion site for leaks, and recheck ketones in 2 to 4 hours. Call your doctor if ketones don’t improve or you feel worse. Memorial Sloan Kettering also advises against exercise when blood glucose is over 250 mg/dL and your ketone test is positive.
Frequently asked questions
Can you smell ketones in urine?
Sometimes. Large amounts can give urine a sweet or fruity odor, yet many people with high ketones notice nothing. Fruity-smelling breath is the sign the ADA lists. Use a strip or a blood meter instead of your nose.
Does ketones in urine mean diabetes?
No. Trace or small results often come from fasting, illness or low-carb eating. Ketones with glucose in urine, heavy thirst and weight loss do raise concern for diabetes, so ask your doctor for a blood sugar test.
Is it normal to have ketones in urine?
After fasting, a long workout or a low-carb day, yes.
Are ketones in urine bad?
Small amounts from fasting or a keto diet are not harmful in healthy adults. They become dangerous when insulin is too low and ketones build faster than the body can clear them, which leads to DKA.
What does a doctor check alongside a ketone result?
Blood glucose first, then symptoms such as vomiting and breathing, food and fluid intake, insulin doses and any SGLT2 inhibitor. With diabetes and high ketones, blood tests confirm or rule out DKA against the three 2024 consensus criteria of high glucose, ketones and acidosis (CCJM 2025).
Sources
- American Diabetes Association. Managing ketones.
- Ascensia Diabetes Care. Ketostix Reagent Strips for Urinalysis, package insert.
- Rodriguez Alvarez P, San Martin VT, Morey-Vargas OL. Hyperglycemic crises in adults: a look at the 2024 consensus report. Cleve Clin J Med. 2025;92(3):152.
- Memorial Sloan Kettering Cancer Center. Diabetic ketoacidosis (DKA) and ketone urine testing.
- MSD Manual Professional Version. Hyperemesis gravidarum.
- US Food and Drug Administration. 510(k) K170587, On Call and Healthy Me Ketone Reagent Strips for Urinalysis (ACON Laboratories).