What initial laboratory tests are recommended for diagnosing euglycemic ketoacidosis?

Laboratory Tests for Diagnosing Euglycemic Diabetic Ketoacidosis

The initial laboratory evaluation for diagnosing euglycemic diabetic ketoacidosis must include plasma glucose, blood urea nitrogen/creatinine, serum ketones (specifically β-hydroxybutyrate), electrolytes with calculated anion gap, arterial blood gases, and urinalysis with urine ketones by dipstick. 1

Essential Laboratory Tests

• Plasma glucose: Must be measured to confirm euglycemia (blood glucose <250 mg/dL) in the presence of ketoacidosis 2
• Arterial blood gases: Essential to document metabolic acidosis (arterial pH <7.3) 1
• Serum bicarbonate: Should be measured to confirm levels ≤15-18 mEq/L 1
• Serum ketones: Specific measurement of β-hydroxybutyrate (βOHB) is preferred over nitroprusside-based methods 1
• Electrolytes with calculated anion gap: Critical to document high anion gap metabolic acidosis 1, 3
• Blood urea nitrogen/creatinine: Important to assess renal function and hydration status 1
• Urinalysis with urine ketones: Provides supporting evidence but should not be used alone for diagnosis 1
• Complete blood count with differential: To evaluate for underlying infection 1

Specific Considerations for Euglycemic DKA

• β-hydroxybutyrate measurement: This is the predominant ketone in DKA and should be specifically measured rather than relying on nitroprusside-based ketone tests that only detect acetoacetate and acetone 1
• Anion gap calculation: Essential for diagnosis as euglycemic DKA presents with high anion gap metabolic acidosis despite normal or near-normal glucose levels 3
• Serum osmolality: Should be calculated to help differentiate from other causes of acidosis 1

Important Diagnostic Pitfalls

• Do not rely solely on blood glucose: The defining characteristic of euglycemic DKA is ketoacidosis with relatively normal glucose levels (<250 mg/dL), which can lead to missed diagnosis 3, 4
• Do not use nitroprusside-based blood ketone tests for monitoring treatment: These tests do not measure βOHB and may show falsely worsening ketosis during treatment as βOHB converts to acetoacetate 1
• Do not rely exclusively on urine ketones: Urine ketone testing alone is insufficient for diagnosis and may be misleading 1
• Consider potential causes: SGLT2 inhibitor use, pregnancy, reduced caloric intake, alcohol consumption, and chronic liver disease can all precipitate euglycemic DKA 5, 2

Diagnostic Algorithm

1. Measure arterial blood gases to confirm metabolic acidosis (pH <7.3) 1
2. Confirm euglycemia (blood glucose <250 mg/dL) 2
3. Measure serum bicarbonate (should be ≤15-18 mEq/L) 1
4. Calculate anion gap (should be elevated) 1, 3
5. Measure serum β-hydroxybutyrate (preferred) or serum ketones 1
6. Exclude other causes of high anion gap metabolic acidosis (lactic acidosis, salicylate toxicity, methanol/ethylene glycol ingestion) 1
7. Obtain complete blood count, electrolytes, BUN/creatinine to assess overall status and identify precipitating factors 1

Following this comprehensive laboratory evaluation will ensure timely diagnosis of euglycemic DKA, which is critical for appropriate management and improved outcomes 3, 4.