Guide to Ketones in Urine

WRITTEN BY

The Levels Team

Updated: 05/22/2025|12 min read

Summary

Ketones are acidic compounds produced by the liver when it breaks down fat, measured to monitor metabolic status during fasting or diets and to detect potentially dangerous conditions in diabetes.

Why It Matters

Your body normally uses glucose, stored as glycogen, as its primary energy source. But it can shift to using fat when carbohydrate intake is restricted or when insulin function is compromised.

Fat metabolism produces ketone bodies that are excreted in urine. The presence of ketones in urine indicates that your body has entered a state called ketosis. Some people, who are on a ketogenic diet, intentionally put their bodies into ketosis to potentially help with weight loss. Intermittent fasting can also trigger mild ketosis as the body uses stored fat for energy during fasting periods.

However, ketones in urine can also signal a metabolic problem. In people with diabetes, especially Type 1 diabetes, ketones may appear when blood glucose levels are dangerously high and insulin is too low. Without adequate insulin, cells can't use glucose for energy, prompting the breakdown of fat instead. This can lead to diabetic ketoacidosis, a serious condition requiring immediate medical attention.

Ketones are also often found in patients who have ongoing nausea, vomiting, or diarrhea. Pregnancy can sometimes cause ketones in urine due to morning sickness and altered metabolism. Similarly, excessive alcohol consumption, or severe illness can trigger ketone production if the body struggles to maintain energy balance. 

This marker is important for monitoring metabolic health, particularly in conditions like diabetes, and during fasting or low-carbohydrate diets.

While low to moderate levels may reflect dietary changes, consistently high levels of ketones may require further testing. 

Associated Symptoms 

Ketones in urine themselves are laboratory findings rather than medical conditions. There are two main scenarios where ketones appear in urine, each with distinct symptom patterns:

Expected or Intentional Ketosis (from low-carb diets, fasting, or pregnancy):

• Mild thirst: Increased need for fluids
• Initial fatigue: Temporary tiredness as the body adapts to using fat for energy
• Decreased appetite: Reduced hunger commonly reported during ketosis
• Mild headache: Temporary symptom during metabolic adaptation

Diabetic Ketoacidosis (a medical emergency in people with diabetes):

• Excessive thirst and urination: Intense thirst and frequent urination due to high blood sugar
• Nausea or vomiting: Gastrointestinal disturbances from blood acidity
• Abdominal pain: Discomfort in the stomach region from acidosis
• Confusion or difficulty concentrating: Altered mental status possibly from neuroinflammation, buildup of ketones, acidosis
• Rapid, deep breathing: Compensatory breathing pattern for metabolic acidosis
• Weakness or extreme fatigue: Profound tiredness from cellular energy crisis

It's important to understand the context of ketones in your urine. If you're following a ketogenic diet, fasting, or pregnant, mild to moderate ketones are often expected. However, in people with diabetes (especially Type 1), elevated ketones alongside high blood sugar and symptoms require immediate medical attention as this could indicate diabetic ketoacidosis, a potentially life-threatening condition.

Clinical Ranges

• Lab Reference Range: Negative

Lifestyle Factors That Can Impact It

Activities that may impact the ketone levels in urine include:

• Very low-carbohydrate or ketogenic diets: Deliberately restricting carbohydrate intake to less than 50 grams daily forces your body to produce ketones as an alternative energy source.
• Intermittent fasting or prolonged fasting: Going without food for extended periods (typically 16+ hours) causes your body to use fat as energy, resulting in ketone production.
• High-intensity exercise: Vigorous physical activity can deplete glycogen stores and promote ketones, particularly if you're fasting.
• Excessive alcohol consumption: Excessive drinking, especially without adequate food intake, can disrupt normal metabolism and lead to ketone production.
• Dehydration: Insufficient fluid intake concentrates urine, potentially making ketone levels appear higher than they actually are in the body. Excessive vomiting or diarrhea can also drive dehydration.

Other Factors That Can Impact It

Genetic Conditions

• Certain genetic mutations affect how the body produces or uses ketones, making them either more or less prone to ketosis under certain conditions.

Medical Conditions

• Diabetes (particularly Type 1): Insulin deficiency prevents cells from utilizing glucose, forcing fat metabolism and ketone production. This can progress to diabetic ketoacidosis, a life-threatening condition where blood becomes acidic.
• Hyperthyroidism: Accelerated metabolism increases energy demands, potentially leading to increased fat breakdown and ketone production.

Medications and Supplements

• SGLT2 inhibitors (like empagliflozin, canagliflozin): These diabetes medications can increase the risk of ketoacidosis even when blood glucose isn't extremely elevated.
• Corticosteroids: Can affect insulin sensitivity and glucose metabolism, potentially affecting ketone production.

Individual Factors

• Pregnancy: Hormonal changes and morning sickness can trigger ketone production, particularly if vomiting limits food intake.
• Stress: Physical or emotional stress triggers hormones that can increase blood glucose and potentially lead to ketone production, particularly in people with diabetes.

Testing Accuracy and Stability

Urine ketone tests are generally reliable for detecting the presence of ketones but may not precisely quantify their concentration. Certain factors can affect results. Note that urine ketone tests reflect ketones excreted hours prior and can lag behind current ketone levels

Factors That Can Affect the Accuracy of Your Test 

• Highly diluted urine (from drinking large amounts of water) may mask ketone levels in urine.
• Dehydration can concentrate urine and potentially inflate ketone readings.
• Certain medications, including levodopa and vitamin C supplements, can affect test accuracy
• Time of day and relation to meals can influence ketone levels

How It Relates to Other Markers

Other tests can provide insights about health status when they're viewed alongside ketones in urine. These tests may include:

• Blood glucose levels: This helps distinguish between diabetic ketoacidosis and dieting ketosis.
• Blood ketone measurement: Blood ketone testing provides real-time ketone levels, whereas urine ketones may reflect production from several hours ago.
• Serum electrolytes (sodium, potassium, chloride, bicarbonate): Ketoacidosis can cause dangerous electrolyte imbalances that require treatment.
• Blood pH and anion gap: Determines the severity of acidosis in ketosis. These measurements help distinguish between ketosis from nutritional intake (normal pH) and dangerous ketoacidosis (low pH, elevated anion gap).
• Hemoglobin A1c: Provides insight into glucose control over the past 2-3 months.
• C-peptide levels: Measures endogenous insulin production to differentiate between Type 1 and Type 2 diabetes.
• Thyroid function tests: Hyperthyroidism can accelerate metabolism and contribute to ketone formation.
• Liver function tests: The liver is the primary site of ketone production. Abnormal liver function may affect ketone metabolism or indicate underlying liver disease.
• Pregnancy test: Essential for women of childbearing age.
• Cortisol levels: Stress hormones like cortisol can increase glucose production and potentially affect ketone metabolism.

What Results May Mean in the Context of Other Markers

• Elevated blood glucose + ketones: This combination, particularly in people with diabetes, may suggest insufficient insulin and potential diabetic ketoacidosis.
• Normal blood glucose + ketones: Can indicate nutritional ketosis from fasting, low-carbohydrate diets, or extended exercise.
• Low blood glucose + ketones: May suggest hypoglycemia with compensatory fat metabolism. This combination can occur during prolonged fasting or in certain metabolic disorders.
• Ketones + protein in urine: Could indicate kidney stress or damage, particularly in the context of uncontrolled diabetes.
• Ketones + acidic urine pH: Can suggest metabolic acidosis, which may occur in diabetic ketoacidosis or certain other metabolic disturbances.

Follow-up Considerations

If the ketone levels are out of average range, your provider may make some of the following recommendations. You should always speak to your doctor if you have medical questions or before making medical decisions.

When Re-Testing May Be Appropriate

• Right away if you have diabetes and moderate to high ketone levels
• After 3-5 days if you're on a ketogenic diet and monitoring nutritional ketosis
• At your next regular checkup if ketones were mildly elevated with no symptoms
• According to your doctor's recommendation if you're pregnant and showed ketones

Additional Testing Your Doctor May Consider

• Comprehensive metabolic panel to assess liver and kidney function
• Blood glucose monitoring
• HbA1c test to evaluate long-term glucose control
• Blood ketone testing (more accurate than urine for quantitative measurement)
• Arterial blood gas analysis if diabetic ketoacidosis is suspected

When Additional Care May Be Warranted

• Seek immediate care if you have diabetes and moderate to high ketones with symptoms like vomiting, extreme thirst, or confusion.
• If you're pregnant and have ketones with nausea or vomiting.
• If you have unexplained weight loss, excessive thirst, or frequent urination.

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