Is ketones in the urine a problem?

Ketones in Urine: Clinical Significance and Management

Ketones in urine are a potential warning sign that requires medical attention, particularly in individuals with diabetes, as they may indicate impending or established diabetic ketoacidosis (DKA), a life-threatening condition. 1, 2

Clinical Significance of Urine Ketones

Ketones in urine can have different clinical implications depending on the context:

Normal Physiological States

• Ketones may appear in urine during:
  • Prolonged fasting
  • Very low carbohydrate diets (<20-30g daily)
  • Prolonged exercise
  • Pregnancy
  • Neonatal period 2, 3

Pathological States

• Diabetic ketoacidosis (DKA): Most serious concern, especially in:
  • Type 1 diabetes patients
  • Patients with history of previous DKA
  • Patients using SGLT2 inhibitors
  • During illness, infection, or missed insulin doses 2, 4
• Alcoholic ketoacidosis: Can present with positive urine ketone readings without hyperglycemia 1
• Starvation ketosis: Due to inadequate carbohydrate intake 2

Interpreting Ketone Measurements

Urine Ketones

• Primarily measures acetoacetate (AcAc) and acetone using nitroprusside reaction
• Does not detect beta-hydroxybutyrate (bOHB), which is the predominant ketone in DKA 1, 5
• As DKA resolves, bOHB is oxidized to AcAc, so urine ketones may paradoxically increase even as DKA is resolving 5

Blood Ketones

• More accurate for DKA diagnosis and monitoring
• Blood ketone levels classification:
  • <0.5 mmol/L: Normal range
  • 0.5-1.5 mmol/L: Mild elevation (may be due to fasting or exercise)
  • 1.5-3.0 mmol/L: Moderate elevation (requires monitoring)

  • 3.0 mmol/L: Dangerous level (requires immediate medical attention)

  • 7.0-8.0 mmol/L: Severe ketoacidosis 2

When to Be Concerned About Ketones in Urine

Urine ketones are concerning in the following situations:

1. Diabetes patients with hyperglycemia: Suggests impending or established DKA 1
2. Patients on SGLT2 inhibitors: These medications increase risk of DKA, sometimes with only mild hyperglycemia (euglycemic DKA) 1, 6
3. Pregnant women with diabetes: Higher risk of DKA 2
4. During illness or infection in diabetes patients: Increased risk of metabolic decompensation 1, 2
5. Large ketonuria (regardless of glucose levels): Requires immediate medical attention 2

Management of Detected Ketones

For Mild to Moderate Ketones

• Increase oral fluid intake (at least 150-200g of carbohydrate-containing fluids daily)
• Take additional short or rapid-acting insulin as advised by healthcare provider
• Monitor blood glucose and ketones frequently (every 2-4 hours)
• Never omit insulin, even when not eating 1, 2, 4

For Large Ketones or Symptoms of DKA

• Seek immediate medical attention
• Early symptoms of DKA include:
  • Drowsiness
  • Flushed face
  • Thirst
  • Loss of appetite
  • Fruity odor on breath
  • Nausea and vomiting
  • Abdominal pain
  • Heavy breathing and rapid pulse 2, 4

Prevention of Ketosis and DKA

• Ensure adequate carbohydrate intake (150-200g daily)
• Maintain adequate hydration
• Never omit insulin doses
• Adjust insulin during illness according to sick day rules
• Monitor blood glucose and ketones during illness or when using SGLT2 inhibitors
• Seek medical advice if symptoms worsen or ketone levels increase 1, 2, 4

Key Pitfalls to Avoid

1. Failing to check for ketones in patients with normal blood glucose: Can miss euglycemic DKA, particularly in patients on SGLT2 inhibitors 2, 6
2. Relying solely on urine ketones for DKA monitoring: Blood bOHB measurement is preferred for diagnosis and monitoring of DKA 1, 5
3. Stopping insulin too early: Continue insulin therapy until ketoacidosis resolves 2
4. Inadequate hydration: Dehydration can worsen ketosis 2

Ketones in urine should never be dismissed, particularly in individuals with diabetes or those taking SGLT2 inhibitors. They require appropriate assessment and management to prevent progression to life-threatening DKA.