Initial Laboratory Assessment for Diabetic Ketoacidosis
Immediately obtain a complete metabolic panel, venous blood gases, complete blood count with differential, urinalysis, serum β-hydroxybutyrate, and electrocardiogram when DKA is suspected. 1
Essential Initial Laboratory Tests
Core Diagnostic Labs (Draw Immediately)
Blood glucose to confirm hyperglycemia (typically >250 mg/dL, though euglycemic DKA can occur with SGLT2 inhibitor use) 1, 2
Venous blood gas to measure pH and bicarbonate—pH <7.3 and bicarbonate <15 mEq/L are diagnostic for DKA 1, 2
Serum electrolytes including sodium, potassium, chloride, and bicarbonate to calculate anion gap 1
Anion gap calculation using [Na⁺] - ([Cl⁻] + [HCO₃⁻]) should be >10-12 mEq/L in DKA 1, 3
Blood urea nitrogen and creatinine to assess renal function and hydration status 4, 1
β-hydroxybutyrate (blood) is the preferred method for diagnosing and monitoring DKA—this is superior to urine ketones 1, 2
Complete blood count with differential to identify infection or other precipitating factors 4, 1
Urinalysis with urine dipstick to screen for infection and assess ketonuria 1
Electrocardiogram to detect cardiac complications and monitor for potassium-related arrhythmias 1
HbA1c to distinguish acute decompensation in well-controlled diabetes from chronic poor control 4, 1
Additional Tests Based on Clinical Suspicion
Bacterial cultures (blood, urine, throat) if infection is suspected, as infection is the most common precipitating factor 4, 2
Chest X-ray if respiratory infection or other pulmonary pathology is suspected 4
Amylase and lipase if pancreatitis is suspected as a precipitating cause 5
Troponin and creatine kinase if myocardial infarction is suspected 5
Hepatic transaminases to evaluate for hepatic involvement 5
Critical Calculation: Corrected Sodium
- Calculate corrected sodium by adding 1.6 mEq/L for every 100 mg/dL glucose above 100 mg/dL to assess true sodium status 1, 2
Severity Classification Based on Initial Labs
Mild DKA
Moderate DKA
Severe DKA
- Venous pH <7.00 1, 2
- Bicarbonate <10 mEq/L 1, 2
- Anion gap >12 mEq/L 1, 3
- Requires intensive monitoring including possible central venous and intra-arterial pressure monitoring 2
Ongoing Monitoring During Treatment
Draw labs every 2-4 hours to measure electrolytes, glucose, BUN, creatinine, osmolality, and venous pH during active treatment 2
Monitor β-hydroxybutyrate every 2-4 hours during treatment, as ketosis resolution takes longer than hyperglycemia correction 2
Follow venous pH and anion gap to monitor acidosis resolution—repeated arterial blood gases are unnecessary after initial diagnosis 2
Resolution Criteria (When to Stop Intensive Monitoring)
DKA is resolved when all of the following are met: 1, 2
- 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, 2
Never use urine ketones for treatment monitoring—the nitroprusside method only measures acetoacetate and acetone, not β-hydroxybutyrate (the predominant ketoacid), and can paradoxically worsen during treatment as β-hydroxybutyrate converts to acetoacetate 1, 2
Never assume normal temperature rules out infection—patients with DKA can be normothermic or even hypothermic despite serious infection, and hypothermia is a poor prognostic sign 4, 1
Never stop monitoring too early—continue β-hydroxybutyrate monitoring until normalized, even after urine ketones clear 1
Initial Treatment Priorities (Based on Lab Results)
Fluid Resuscitation
- Begin aggressive fluid resuscitation with isotonic saline at 15-20 mL/kg/hour to restore circulatory volume 2
Potassium Management (Critical First Step)
- If potassium <3.3 mEq/L: Hold insulin, aggressively replace potassium first 1, 2
- If potassium 3.3-5.5 mEq/L: Add 20-30 mEq/L potassium to IV fluids once urine output confirmed 2
- If potassium >5.5 mEq/L: Hold potassium replacement, recheck in 2 hours 2