At what level are ketone (ketone bodies) levels considered elevated in diabetic ketoacidosis (DKA)?

Ketone Levels in Diabetic Ketoacidosis (DKA)

In diabetic ketoacidosis (DKA), serum ketone bodies are considered significantly elevated when beta-hydroxybutyrate (BHB) levels are ≥3.0 mmol/L in children and ≥3.8 mmol/L in adults. 1

Diagnostic Criteria for DKA

DKA is diagnosed based on a triad of findings:

1. Hyperglycemia: Blood glucose >250 mg/dL
2. Metabolic acidosis:
   • Arterial pH <7.3
   • Serum bicarbonate <15 mEq/L
3. Elevated ketones: Positive serum or urine ketones

The severity of DKA can be classified as follows:

Severity	Arterial pH	Serum Bicarbonate (mEq/L)
Mild	7.25-7.30	15-18
Moderate	7.00-7.24	10 to <15
Severe	<7.00	<10

2, 1

Ketone Measurement Methods

Blood Ketone Testing (Preferred Method)

• Beta-hydroxybutyrate (BHB): This is the predominant ketone body in DKA and the most accurate indicator of ketosis.
• Diagnostic threshold:
  • ≥3.0 mmol/L in children
  • ≥3.8 mmol/L in adults 1
• Recent research suggests an optimal cut-off value of 6.3 mmol/L of beta-hydroxybutyrate for DKA diagnosis 3

Urine Ketone Testing

• Less reliable than blood testing
• Measures primarily acetoacetic acid and acetone, not beta-hydroxybutyrate
• Can show false positives with certain medications (e.g., captopril)
• Can show false negatives with highly acidic urine

Important Limitation of Nitroprusside Method

The nitroprusside method (commonly used in urine dipsticks) only measures acetoacetic acid and acetone, not beta-hydroxybutyrate, which is the most abundant ketone body in DKA. This can lead to misleading results during treatment as beta-hydroxybutyrate is converted to acetoacetic acid, potentially suggesting worsening ketosis when the patient is actually improving. 2, 1

Special Considerations

Euglycemic DKA

• Some patients may present with normal or near-normal blood glucose levels (<200 mg/dL) but still have significant ketoacidosis 4
• Common with SGLT2 inhibitor use, pregnancy, reduced caloric intake, alcohol consumption, or recent insulin use
• Ketone testing is essential regardless of glucose levels in high-risk patients

Resolution Criteria for DKA

DKA is considered resolved when:

• Glucose <200 mg/dL
• Serum bicarbonate ≥18 mEq/L
• Venous pH ≥7.3
• BHB <1.5 mmol/L 1

Clinical Implications

1. Always measure ketones in patients with diabetes presenting with:

   • Acute illness
   • Persistent hyperglycemia
   • Symptoms of ketoacidosis (nausea, vomiting, abdominal pain)
   • Pregnancy
   • Use of SGLT2 inhibitors (regardless of glucose level)

2. Blood ketone measurement is preferred over urine ketone testing for accuracy

3. Monitor ketone levels during treatment to assess resolution of DKA, rather than relying solely on glucose levels

4. Be aware of potential false readings with the nitroprusside method during treatment

By understanding the appropriate ketone thresholds for DKA diagnosis and monitoring, clinicians can ensure timely intervention and appropriate management of this serious metabolic complication.