Essential Bloodwork for Diabetic Ketoacidosis (DKA)
Immediately obtain a complete metabolic panel, venous blood gases, complete blood count with differential, urinalysis, serum ketones (preferably β-hydroxybutyrate), and electrocardiogram upon presentation of suspected DKA. 1
Initial Laboratory Panel
Core Diagnostic Tests
- Blood glucose: Required to confirm hyperglycemia (typically >250 mg/dL, though euglycemic DKA can occur) 2, 1
- Venous blood gas: Measure pH and bicarbonate to assess acidosis severity (pH <7.3, bicarbonate <15 mEq/L diagnostic for DKA) 1
- Serum electrolytes: Sodium, potassium, chloride, and bicarbonate to calculate anion gap 2, 1
- Anion gap calculation: Use formula [Na⁺] - ([Cl⁻] + [HCO₃⁻]); should be >10-12 mEq/L in DKA 1, 3
- Blood urea nitrogen (BUN) and creatinine: Assess renal function and hydration status 2, 1
- Serum osmolality: Evaluate hyperosmolar state 2
Ketone Measurement (Critical)
- β-hydroxybutyrate (blood): This is the preferred method for diagnosing and monitoring DKA 1, 4
- Avoid relying on urine ketones or nitroprusside-based tests: These only measure acetoacetate and acetone, completely missing β-hydroxybutyrate—the predominant ketoacid in DKA 1
- Common pitfall: During treatment, β-hydroxybutyrate converts to acetoacetate, making nitroprusside tests paradoxically appear worse even as the patient improves 1
Additional Essential Tests
- Complete blood count with differential: Identify infection or other precipitating factors 2, 1
- Urinalysis with urine dipstick: Screen for infection and assess ketonuria 2
- Electrocardiogram: Detect cardiac complications and monitor for potassium-related arrhythmias 2, 1
- HbA1c: Distinguish acute decompensation in well-controlled diabetes from chronic poor control 2
Corrected Values to Calculate
- Corrected sodium: Add 1.6 mEq/L for every 100 mg/dL glucose above 100 mg/dL 1
- Anion gap: Essential for confirming high anion gap metabolic acidosis and monitoring resolution 1, 3
Additional Tests Based on Clinical Suspicion
If Infection Suspected
- Bacterial cultures: Blood, urine, and throat cultures 2, 1
- Chest X-ray: If respiratory symptoms present 2
If Specific Complications Suspected
- Amylase and lipase: If pancreatitis suspected 5
- Hepatic transaminases: If liver involvement suspected 5
- Troponin and creatine kinase: If myocardial infarction suspected 5
- Phosphate level: Monitor during treatment, especially if levels approach lower limits of normal 2
Monitoring Frequency During Treatment
Draw blood every 2-4 hours during active treatment to measure: 1
- Glucose
- Electrolytes (especially potassium)
- BUN and creatinine
- Serum osmolality
- Venous pH
- β-hydroxybutyrate
Important Monitoring Notes
- Venous pH is adequate for monitoring after initial diagnosis; repeated arterial blood gases are unnecessary 1, 6
- Venous pH typically runs 0.03 units lower than arterial pH 1
- Ketonemia takes longer to clear than hyperglycemia, requiring continued monitoring even after glucose normalizes 1
Severity Classification Based on Labs
Mild DKA
Moderate DKA
Severe DKA
- Venous pH: <7.00
- Bicarbonate: <10 mEq/L
- Anion gap: >12 mEq/L
- Requires intensive monitoring including possible central venous pressure monitoring 1, 3
Resolution Criteria (When to Stop Intensive Monitoring)
DKA is resolved when all of the following are met: 1
- Glucose <200 mg/dL
- Serum bicarbonate ≥18 mEq/L
- Venous pH >7.3
- Anion gap ≤12 mEq/L
Critical Pitfalls to Avoid
- Never delay potassium measurement: If initial potassium <3.3 mEq/L, delay insulin and aggressively replace potassium first to prevent fatal arrhythmias 1
- Don't stop monitoring too early: Continue β-hydroxybutyrate monitoring until normalized, even after urine ketones clear 1
- Don't use urine ketones for treatment monitoring: They are unreliable and can be misleading during treatment 1
- Don't assume normal temperature rules out infection: Patients can be normothermic or hypothermic despite serious infection; hypothermia is a poor prognostic sign 2