What lab indicators are used to diagnose euglycemic diabetic ketoacidosis (DKA)?

Laboratory Indicators for Diagnosing Euglycemic Diabetic Ketoacidosis (DKA)

Blood β-hydroxybutyrate (bOHB) measurement is the most accurate and preferred method for diagnosing euglycemic DKA, combined with evidence of metabolic acidosis despite normal blood glucose levels (<200 mg/dL).

Essential Diagnostic Criteria for Euglycemic DKA

Euglycemic DKA is characterized by the following laboratory findings:

• Blood glucose <200 mg/dL (defining feature of euglycemic DKA, compared to traditional DKA where glucose is >250 mg/dL) 1, 2
• Elevated blood β-hydroxybutyrate (bOHB) - the preferred and most accurate ketone measurement 3, 4
• Venous pH <7.3 (indicating acidosis) 3, 4
• Serum bicarbonate <18 mEq/L 3, 4
• Elevated anion gap (>12 mEq/L) 1, 2

Recommended Laboratory Tests

A comprehensive laboratory evaluation should include:

• Blood glucose (must be <200 mg/dL for euglycemic DKA diagnosis) 1, 2
• Serum β-hydroxybutyrate (bOHB) - optimal cutoff value for DKA is ≥6.3 mmol/L 4, 5
• Venous blood gases to determine pH 3
• Serum electrolytes (sodium, potassium, chloride) 3
• Serum bicarbonate 3
• Calculation of anion gap: [Na⁺] - ([Cl⁻] + [HCO₃⁻]) 3, 4
• Blood urea nitrogen (BUN) and creatinine to assess renal function 3
• Complete blood count 6

Advantages of Blood β-hydroxybutyrate Testing

• bOHB is the predominant ketone body in DKA, making its measurement more accurate than other methods 3, 4
• Point-of-care testing for bOHB has high sensitivity (98%) and specificity (85%) for diagnosing DKA 7
• bOHB testing can detect ketosis earlier than traditional methods 4
• bOHB values correlate strongly with anion gap (r = 0.66) and serum bicarbonate (r = -0.69) 7

Limitations of Traditional Ketone Testing

• Nitroprusside-based tests (urine ketone strips or serum ketone tests) only measure acetoacetate and acetone, not bOHB 3
• During treatment of DKA, bOHB converts to acetoacetate, which can falsely suggest worsening ketosis if using nitroprusside methods 3
• Urine ketones have high negative predictive value but limited ability to quantify the degree of ketosis 3, 4

Monitoring During Treatment

• Blood glucose, electrolytes, BUN, creatinine, venous pH, and anion gap should be monitored every 2-4 hours during treatment 3, 4
• Blood bOHB is the preferred method for monitoring ketosis resolution 3, 4
• Do not use nitroprusside-based blood ketone tests to monitor treatment of DKA 3, 4

Criteria for Resolution of Euglycemic DKA

Resolution of euglycemic DKA is indicated by:

• Normalized anion gap (≤12 mEq/L) 4
• Serum bicarbonate ≥18 mEq/L 3, 4
• Venous pH >7.3 3, 4
• Decreasing blood bOHB levels 3, 4

Clinical Pearls

• High clinical suspicion is required to diagnose euglycemic DKA as normal blood glucose levels can mask the underlying ketoacidosis 1, 2
• Common causes of euglycemic DKA include SGLT2 inhibitor use, pregnancy, reduced caloric intake, alcohol consumption, and recent insulin use 1, 2
• Check blood pH and ketones in ill patients with diabetes regardless of blood glucose levels 1
• Point-of-care bOHB testing can identify DKA at triage, even when glucose levels are not significantly elevated 7