Diagnostic Cut-off Values for Diabetic Ketoacidosis (DKA)
The diagnostic cut-off values for DKA include blood glucose >250 mg/dL, arterial pH <7.3, serum bicarbonate <18 mEq/L, and the presence of ketones in blood or urine. 1
Blood Glucose Criteria
- Classic DKA: Blood glucose >250 mg/dL 2, 1
- Euglycemic DKA: Blood glucose <200 mg/dL (while still exhibiting metabolic acidosis and ketosis) 1
- Hyperosmolar Hyperglycemic State (HHS): Blood glucose >600 mg/dL 2
Acid-Base Parameters
DKA severity can be classified based on arterial pH and serum bicarbonate levels:
| Severity | Arterial pH | Serum Bicarbonate (mEq/L) |
|---|---|---|
| Mild | 7.25-7.30 | 15-18 |
| Moderate | 7.00-7.24 | 10 to <15 |
| Severe | <7.00 | <10 |
Ketone Measurements
- Serum ketones: Must be positive in DKA 2
- β-hydroxybutyrate: Optimal cut-off value for diagnosis of DKA is 6.3 mmol/L 3
- Acetoacetate: Optimal cut-off value for diagnosis of DKA is 1.4 mmol/L 3
- Total ketone body: Optimal cut-off value for diagnosis of DKA is 8.0 mmol/L 3
Other Important Parameters
- Anion gap: >10 mEq/L in mild DKA, >12 mEq/L in moderate to severe DKA 2
- Effective serum osmolality: Variable in DKA, >320 mOsm/kg in HHS 2
- Calculation: 2[measured Na (mEq/L)] + glucose (mg/dL)/18 2
Monitoring Resolution of DKA
Resolution of DKA is defined by:
Important Clinical Considerations
Preferred monitoring method: Direct measurement of β-hydroxybutyrate in blood is preferred over urine ketones for monitoring DKA resolution 2, 1
Nitroprusside method limitations: This method only measures acetoacetic acid and acetone, not β-hydroxybutyrate (the strongest and most prevalent acid in DKA) 2
Ketone conversion during treatment: During therapy, β-hydroxybutyrate is converted to acetoacetic acid, which may falsely suggest worsening ketosis when using nitroprusside method 2
Euglycemic DKA awareness: Be alert for euglycemic DKA, especially in patients taking SGLT2 inhibitors, pregnant patients, or those with reduced food intake 1, 4
Laboratory monitoring frequency: During DKA treatment, blood should be drawn every 2-4 hours for electrolytes, glucose, BUN, creatinine, osmolality, and venous pH 2, 1
The cut-off values for DKA diagnosis are critical for prompt identification and appropriate management of this potentially life-threatening condition. Using these parameters correctly helps differentiate DKA from other metabolic disorders and guides proper treatment decisions.