Metabolic Acidosis

Diagnosis and Monitoring

• The American Diabetes Association recommends monitoring venous pH, serum bicarbonate, and anion gap to diagnose metabolic acidosis, with thresholds of venous pH <7.3, serum bicarbonate <15-18 mEq/L, and anion gap >10 mEq/L 1
• Blood β-hydroxybutyrate levels are the preferred method for monitoring DKA resolution, with a threshold of <1.5 mmol/L (sensitivity 83%, specificity 87%) 1
• The American Diabetes Association recommends monitoring blood glucose every 1-2 hours, electrolytes, venous pH, and anion gap every 2-4 hours during treatment 1
• DKA can be diagnosed by the triad of hyperglycemia (blood glucose >250 mg/dL), metabolic acidosis (pH <7.3, bicarbonate <15 mEq/L), and elevated ketones in blood or urine, with a BHB level of ≥3.0 mmol/L in children and ≥3.8 mmol/L in adults considered diagnostic in the presence of uncontrolled diabetes 2, 3, 4

• The reliability and limitations of different ketone tests are as follows:

  | Test | Reliability for DKA | Limitations | |------|---------------------|-------------| | β-Hydroxybutyric acid | Highest | None significant for diagnosis | | Acetoacetate | Lower | Doesn't measure the predominant ketone in DKA; may underestimate total ketone concentration 4 | | Acetone | Lowest | Minor component; may underestimate total ketone concentration | | Glucose level | Poor | Poor correlation with ketosis; euglycemic DKA possible (especially with SGLT2 inhibitors) 4

• Blood ketone testing methods that quantify beta-hydroxybutyrate are preferred over urine ketone testing for diagnosing and monitoring ketoacidosis, due to the limitations of urine ketone tests 5, 2, 6

• DKA severity can be classified based on arterial pH and serum bicarbonate levels, with severity categorized as:

  | 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 | 2

Treatment and Resolution

• Initial fluid therapy with isotonic saline (0.9% NaCl) at 15-20 ml/kg/h during the first hour is recommended, followed by insulin therapy after initial fluid resuscitation, and frequent monitoring of glucose, electrolytes, and acid-base status is crucial, as stated by the American Diabetes Association and the American Academy of Emergency Medicine 6, 2, 4
• Traditional DKA resolution criteria include a glucose level <200 mg/dL, serum bicarbonate ≥18 mEq/L, and venous pH ≥7.3, as defined by the American Diabetes Association 2
• A BHB value of <1.5 mmol/L is also used to define resolution of DKA, having a sensitivity of 83% and specificity of 87% 1, 4
• DKA is considered resolved when glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, venous pH ≥7.3, and blood β-hydroxybutyrate <1.5 mmol/L 1

Common Symptoms and Signs

• Common symptoms and signs of DKA include polyuria and polydipsia, nausea and vomiting, abdominal pain, weight loss, severe fatigue, dyspnea, and altered mental status or severe dehydration 1
• A comprehensive laboratory panel for diabetic patients presenting with hypotension should include complete blood count, comprehensive metabolic panel, urinalysis, serum ketones, and arterial or venous blood gas analysis to rule out life-threatening complications, as recommended by the American Diabetes Association 7
• Orthostatic vital signs, including blood pressure and heart rate, should be documented in lying, sitting, and standing positions for patients with suspected orthostatic hypotension, as recommended by the European Society of Cardiology 8, 9
• Serum potassium levels should be checked, especially in patients on ACE inhibitors, ARBs, or diuretics, as recommended by the American Diabetes Association 7

Prevention and Management

• Patient education on sick day management and ketone monitoring is crucial to prevent DKA, and patients should be encouraged to contact their diabetes care team immediately if concerned about DKA 10, 4
• Regular ketone monitoring is recommended for high-risk individuals, including those with type 1 diabetes, pregnant women, and patients taking SGLT2 inhibitors, with blood β-hydroxybutyrate testing preferred over urine ketone testing 10, 1
• Consider continuous ketone monitoring for high-risk patients, especially those with type 1 diabetes, pregnancy, on SGLT2 inhibitors, with recurrent DKA, or on low carbohydrate diets 10, 11
• Home monitoring supplies for BHB should be provided to patients at risk for DKA, including those with type 1 diabetes, history of DKA, and patients treated with SGLT2 inhibitors 11
• SGLT2 inhibitor users should measure ketones at any sign of illness regardless of glucose levels due to risk of euglycemic ketoacidosis, with each 0.1 mmol/L increase in baseline BHB increasing DKA risk by 18%, and each 0.1 mmol/L increase from baseline increasing risk by 8% 1, 4, 12, 11