---
title: "Ketones in urine: what they mean, causes and when they are an emergency"
type: biomarker-interpretation
url: "https://www.test-well.com/biomarkers/ketones-in-urine/high"
biomarker: Ketones in Urine
direction: high
reviewed_at: 2026-11-03
review_status: reviewed
date_published: 2026-09-05
---

# Ketones in urine: what they mean, causes and when they are an emergency

> Ketones in urine mean the body is burning fat for fuel. After an overnight fast, on a ketogenic diet, after a long workout, in early pregnancy or during a vomiting illness, small ketones are expected and harmless. In someone with diabetes, moderate or large ketones — especially with a glucose above 250 mg/dL, nausea, vomiting, abdominal pain or rapid breathing — mean diabetic ketoacidosis until a blood ketone and metabolic panel prove otherwise.


## When does this result need same-day care?

- Moderate or large ketones with a blood glucose above 250 mg/dL, or any ketones with vomiting, abdominal pain, rapid breathing, drowsiness or confusion — emergency care
- Any ketones in an unwell person taking an SGLT2 inhibitor, regardless of glucose — emergency care
- Ketones with heavy recent drinking and vomiting, or in a pregnant woman who cannot keep fluids down — same-day assessment

## What is the normal range for Ketones in Urine?

Expected result: negative. Ketones (mainly acetoacetate) on the urine dipstick, the by-product of burning fat for fuel. Normally negative; graded trace (5 mg/dL) to large (80–160 mg/dL).
Fasting, a ketogenic or very-low-carbohydrate diet, prolonged exercise, vomiting and pregnancy produce small to moderate ketones; large ketones with a high blood glucose, thirst, nausea or rapid breathing is diabetic ketoacidosis, an emergency.

## What are the common causes of high Ketones in Urine?

1. Fasting for more than 12–18 hours, skipped meals, crash dieting and eating disorders
2. A ketogenic or very-low-carbohydrate diet — ketones are the intended result
3. Prolonged or intense exercise, especially fasted
4. Pregnancy — fasting ketosis develops faster, and hyperemesis produces moderate to large ketones from starvation and dehydration
5. Vomiting, diarrhea or any illness with poor intake; in children, almost any febrile illness
6. Heavy alcohol use — alcoholic ketoacidosis after a binge with vomiting and little food
7. Diabetic ketoacidosis — insulin deficiency in type 1 diabetes (missed doses, pump failure, new diagnosis), severe illness or infection in type 2 diabetes
8. Euglycemic ketoacidosis on SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin, ertugliflozin) — the glucose can be near normal
9. False positives — captopril, mesna, N-acetylcysteine, levodopa, valproate metabolites and strongly pigmented urine; isopropyl alcohol ingestion produces true acetone

## What symptoms go with high Ketones in Urine?

- None with fasting, dietary or exercise ketones beyond a fruity or acetone smell on the breath
- Thirst, frequent urination, dry mouth and fatigue as ketones rise with high glucose
- Nausea, vomiting, abdominal pain and loss of appetite
- Deep, rapid breathing, drowsiness and confusion in ketoacidosis

## What do clinicians usually check next?

- Check a blood glucose; with diabetes, a blood ketone (beta-hydroxybutyrate) — the urine strip misses the dominant early ketone and lags in both directions
- A basic metabolic panel for bicarbonate and the anion gap when ketones are moderate or large or any symptoms are present; ketoacidosis is bicarbonate below 18 mmol/L with a raised gap
- Follow your sick-day plan if you have diabetes — extra rapid-acting insulin and fluids as instructed, never stopping basal insulin — and seek care if ketones do not fall
- Without diabetes: eat a carbohydrate-containing meal, hydrate and repeat; fasting, diet and exercise ketones clear within hours
- In pregnancy: food and fluids, then assessment for hyperemesis and intravenous fluids if ketones persist or fluids cannot be kept down
- Persistent ketones in someone eating normally: glucose, hemoglobin A1c, a metabolic panel and a review of medications and alcohol

Follow-up tests at TestWell: [Basic Metabolic Panel](https://www.test-well.com/tests/basic-metabolic-panel) ($17.99), [Hemoglobin A1c Test](https://www.test-well.com/tests/hemoglobin-a1c) ($18.99), [Glucose Test](https://www.test-well.com/tests/glucose-basic) ($14.99).

## How do you recheck Ketones in Urine?

| Test or panel | Type | Price | Fasting | Results |
| --- | --- | --- | --- | --- |
| [Kidney Health Panel](https://www.test-well.com/tests/kidney-health-panel) | Panel (4 tests) | $64.99 | Yes | 2–4 business days |
| [Early Pregnancy Panel](https://www.test-well.com/tests/prenatal-screening-panel) | Panel (9 tests) | $249.99 | No | 3–5 business days |
| [Men's Total Body Advanced Panel](https://www.test-well.com/tests/mens-total-body-advanced-panel) | Panel (65 tests) | $999.99 | Yes | 5–10 business days |
| [Complete Urinalysis Test](https://www.test-well.com/tests/urinalysis) | Test | $17.99 | No | 1–3 business days |

Plus one $6 lab processing fee per order; physician authorization included.

## Common questions

### What causes ketones in urine?

Burning fat for fuel: fasting, a ketogenic or low-carbohydrate diet, long exercise, pregnancy, a vomiting illness and heavy drinking all produce them in people without diabetes, usually at trace to small levels that clear with a meal. In diabetes, ketones mean insulin is insufficient, and moderate or large ketones with a high glucose or any feeling of illness are treated as ketoacidosis until proven otherwise.

### Are ketones in urine during pregnancy dangerous?

Small morning ketones are common in pregnancy because fasting ketosis develops faster, and they respond to eating. Persistent moderate or large ketones — typically with severe nausea and vomiting — signal starvation and dehydration (hyperemesis) and need assessment and fluids. In a pregnant woman with diabetes, ketones are managed as a possible ketoacidosis and are urgent.

### What level of ketones in urine is dangerous?

Moderate (about 40 mg/dL) or large (80–160 mg/dL) ketones in someone with diabetes, particularly with a glucose above 250 mg/dL or symptoms of nausea, vomiting, abdominal pain or rapid breathing, is the danger level and needs emergency care. Without diabetes the same readings after a long fast or a stomach bug are far less likely to mean acidosis, but should still be explained and rechecked after eating.

### Why are urine ketones still positive when I feel better?

The dipstick detects acetoacetate, and as ketoacidosis resolves the body converts beta-hydroxybutyrate back into acetoacetate, so urine ketones can rise or linger for a day after the blood has cleared. Urine ketones are also a record of the hours since the bladder last emptied. Blood ketone levels are the better guide to recovery.

## Related

- [Ketones in Urine reference ranges](https://www.test-well.com/biomarkers/ketones-in-urine)
- [Protein in Urine reference range](https://www.test-well.com/biomarkers/protein-in-urine)
- [Blood in Urine reference range](https://www.test-well.com/biomarkers/blood-in-urine)
- [Leukocyte Esterase reference range](https://www.test-well.com/biomarkers/leukocyte-esterase)

## Sources

- [MedlinePlus (NIH) — Ketones in Urine](https://medlineplus.gov/lab-tests/ketones-in-urine/)
- [American Diabetes Association — Standards of Care in Diabetes 2024: diabetic ketoacidosis](https://diabetesjournals.org/care/issue/47/Supplement_1)
- [Simerville JA, et al. Urinalysis: a comprehensive review. Am Fam Physician. 2005;71(6):1153–62](https://www.aafp.org/pubs/afp/issues/2005/0315/p1153.html)

---

Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-11-03. Review policy: https://www.test-well.com/reviewers/youmna-distefano-md

Canonical page: https://www.test-well.com/biomarkers/ketones-in-urine/high
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Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.