What does it mean to have ketones in urine and how is it treated?

What Ketones in Urine Mean and How to Treat Them

Clinical Significance

Ketones in urine indicate your body is breaking down fat for energy instead of using glucose, which can range from a normal physiological response to fasting or pregnancy to a medical emergency like diabetic ketoacidosis (DKA). 1

The presence of urine ketones is highly sensitive for DKA with high negative predictive value, making it useful for ruling out this life-threatening condition. 1 However, understanding the context is critical:

In People With Diabetes (Especially Type 1):

• Urine ketones suggest insufficient insulin and may indicate impending or established DKA, which requires immediate action. 2
• Even mild ketosis (1+ ketones) in ketosis-prone individuals requires monitoring and potential intervention. 2
• You must test for ketones during acute illness, stress, or when blood glucose exceeds target ranges. 2, 3

In Non-Diabetic Individuals:

• Ketones may represent normal physiological responses to fasting or prolonged exercise. 2, 4
• Up to 30% of first morning urine specimens from pregnant women show positive ketones as a normal finding. 2, 5

Critical Diagnostic Pitfall

Standard urine ketone tests using nitroprusside reagents only detect acetoacetate and NOT β-hydroxybutyrate (the predominant ketone in DKA), which can severely underestimate total ketone body concentration and delay recognition of DKA. 1, 2, 5 This is particularly dangerous because:

• During active DKA, β-hydroxybutyrate predominates in blood. 4
• As DKA resolves, β-hydroxybutyrate converts to acetoacetate, so urine ketones may paradoxically increase even as the patient improves. 4
• Blood ketone testing measuring β-hydroxybutyrate is strongly preferred over urine testing for diagnosis and monitoring. 1, 2, 3

Treatment Algorithm

For People With Diabetes Who Have Ketones:

Immediate Actions ("Sick Day Rules"): 1, 2, 3

1. Increase oral fluid intake to prevent dehydration
2. Monitor blood glucose and ketone levels every 3-4 hours
3. Administer additional short or rapid-acting insulin if blood glucose is elevated
4. If blood glucose is normal but ketones are elevated, consume carbohydrates along with insulin to suppress ketone production 2

Seek Emergency Medical Care If: 3

• Unable to tolerate oral hydration due to vomiting
• Blood glucose levels do not improve with insulin
• Altered mental status develops
• Ketone levels continue to increase despite interventions
• Symptoms of DKA develop (abdominal pain, nausea, vomiting, rapid breathing)

Special High-Risk Populations:

SGLT2 Inhibitor Users: 3, 6

• At increased risk for euglycemic DKA (DKA with relatively normal blood glucose)
• Must maintain high suspicion for DKA even when glucose is not severely elevated
• Should be used with extreme caution in type 1 diabetes with extensive counseling and close monitoring 6

Pregnant Women: 3, 5

• May present with euglycemic DKA
• Should seek immediate medical attention if ketones are elevated
• Blood β-hydroxybutyrate is the preferred test over urine ketones 5
• Never rely solely on urine ketones to rule out DKA in pregnancy 5

Additional Testing Considerations

False Results to Watch For: 2

• False-positive: Highly colored urine, sulfhydryl drugs (including captopril), prolonged air exposure of test strips
• False-negative: Highly acidic urine specimens, expired test strips

Preferred Testing Method: 1, 2, 3

• Blood β-hydroxybutyrate measurement is superior to urine ketone testing
• Should be used for diagnosis of DKA and may be used for monitoring during treatment
• Blood ketone meters are available for home use and increase likelihood of testing during illness 1

When Ketones Are NOT an Emergency

For non-diabetic individuals, mild ketonuria may simply require: 2

• Increasing oral fluid and carbohydrate intake
• Monitoring for progression if symptoms develop
• No specific treatment if related to normal fasting or early pregnancy