Can we label this finding as diabetic ketoacidosis?

Can We Diagnose Diabetic Ketoacidosis?

Yes, you can diagnose diabetic ketoacidosis (DKA) when all three core criteria are simultaneously present: hyperglycemia (plasma glucose >250 mg/dL), metabolic acidosis (arterial pH <7.3 AND serum bicarbonate <18 mEq/L), and positive ketones in blood or urine. 1

Core Diagnostic Criteria

To label a finding as DKA, you must document all three of the following simultaneously:

• Hyperglycemia: Plasma glucose >250 mg/dL 2, 1
• Metabolic acidosis: Arterial pH <7.3 AND serum bicarbonate <18 mEq/L 2, 1
• Ketosis: Positive serum or urine ketones (preferably β-hydroxybutyrate) 1

All three criteria must be met together—meeting only one or two is insufficient for the diagnosis. 1

Severity Stratification Once Diagnosed

Once you've confirmed DKA, classify severity based on the degree of acidosis:

• Mild DKA: pH 7.25–7.30, bicarbonate 15–18 mEq/L, anion gap >10 mEq/L, patient alert 2, 1
• Moderate DKA: pH 7.00–7.24, bicarbonate 10 to <15 mEq/L, anion gap >12 mEq/L, patient alert/drowsy 2, 1
• Severe DKA: pH <7.00, bicarbonate <10 mEq/L, anion gap >12 mEq/L, patient stuporous/comatose 2, 1

Critical Ketone Measurement Pitfall

Use β-hydroxybutyrate (β-OHB) measurement in blood as the preferred method for diagnosing DKA, not nitroprusside-based tests. 1 This is crucial because:

• Nitroprusside methods (urine dipsticks, serum tablets) only detect acetoacetate and acetone, NOT β-OHB, which is the predominant ketone in DKA 3, 1
• During treatment, β-OHB converts to acetoacetate, making nitroprusside tests falsely suggest worsening ketosis when the patient is actually improving 1
• Point-of-care β-OHB testing at triage has 98% sensitivity and 85% specificity for DKA diagnosis 4

Special Consideration: Euglycemic DKA

Approximately 10% of DKA presentations are euglycemic (glucose <200–250 mg/dL), which can delay diagnosis if you rely solely on hyperglycemia. 1 For euglycemic DKA:

• You can still diagnose DKA when glucose is <250 mg/dL IF the patient has documented hyperglycemia at any point or a prior diabetes history, PLUS the required metabolic acidosis (pH <7.3, bicarbonate <18 mEq/L) and elevated β-OHB 1
• Common precipitating factors include SGLT2 inhibitor use (most frequent modern cause), reduced caloric intake/fasting, pregnancy, alcohol consumption, and chronic liver disease 1, 5, 6

Essential Differential Diagnosis

DKA must be distinguished from other causes of high anion gap metabolic acidosis, particularly alcoholic ketoacidosis (AKA). 1 Key differences:

• Alcoholic ketoacidosis: Glucose typically normal, low, or only mildly elevated (rarely >250 mg/dL), often with frank hypoglycemia; less severe acidosis; clinical history of alcohol use 3, 1
• Starvation ketosis: Serum bicarbonate typically not lower than 18 mEq/L, less severe acidosis, prolonged fasting history 1

Required Initial Laboratory Workup

When DKA is suspected, obtain:

• Plasma glucose, arterial blood gas (pH, bicarbonate) or venous pH 1
• Serum electrolytes with calculated anion gap 2, 1
• Serum β-OHB (preferred) or serum/urine ketones 1
• Blood urea nitrogen/creatinine, serum osmolality 2, 1
• Complete blood count with differential, urinalysis, electrocardiogram 2, 1, 5
• Consider bacterial cultures if infection suspected 2

Resolution Criteria

DKA is considered resolved when glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, and venous pH >7.3. 1

Alkalemic Variant Warning

Be aware that 23% of DKA cases present with pH >7.4 (diabetic ketoalkalosis) due to concurrent metabolic alkalosis or respiratory alkalosis, yet still have severe ketoacidosis requiring full DKA treatment. 7 These patients still have increased anion gap metabolic acidosis and elevated β-OHB despite the alkalemic pH. 7