What are the necessary steps for further workup and management of a patient with Diabetic Ketoacidosis (DKA)?

DKA Further Workup

Begin with immediate laboratory evaluation including plasma glucose, arterial blood gases, serum ketones (preferably β-hydroxybutyrate), electrolytes with calculated anion gap, serum osmolality, blood urea nitrogen, creatinine, complete blood count with differential, urinalysis with urine ketones, and electrocardiogram. 1, 2, 3

Initial Diagnostic Laboratory Panel

Essential Labs to Draw Immediately

• Plasma glucose - diagnostic threshold >250 mg/dL (though euglycemic DKA can occur with SGLT2 inhibitors) 1, 4
• Arterial blood gases - pH <7.30 confirms DKA 1, 3
• Serum bicarbonate - <18 mEq/L for DKA diagnosis 1, 3
• Serum ketones - β-hydroxybutyrate measurement is preferred over nitroprusside method, which only detects acetoacetate and acetone 2
• Electrolytes with calculated anion gap - anion gap >10 mEq/L (calculated as Na - [Cl + HCO3]) 1, 3
• Serum osmolality - calculated as 2[Na] + glucose/18 1
• Blood urea nitrogen and creatinine - assess renal function and hydration status; higher BUN is a risk factor for cerebral edema 1, 2
• Complete blood count with differential - evaluate for infection as precipitating cause 1, 3
• Urinalysis with urine ketones - positive ketones support diagnosis 1, 3
• Electrocardiogram - detect cardiac complications and monitor for arrhythmias from electrolyte abnormalities 1, 2

Additional Workup Based on Clinical Presentation

• Blood and urine cultures - obtain if infection suspected as precipitating cause 1, 3
• Chest radiograph - if pneumonia suspected 4
• Cardiac biomarkers (troponin, creatine kinase) - if myocardial infarction suspected as precipitant 2, 4
• Amylase and lipase - if abdominal pain prominent to evaluate for pancreatitis 4
• Hepatic transaminases - consider if liver pathology suspected 4
• Hemoglobin A1C - assess chronic glycemic control 4
• Throat cultures - if pharyngitis suspected 1

Ongoing Monitoring Requirements

Frequent Laboratory Monitoring During Treatment

• Blood glucose every 1-2 hours until stable, then every 2-4 hours 2, 5
• Serum electrolytes, glucose, BUN, creatinine, osmolality, and venous pH every 2-4 hours to guide therapy adjustments 2, 3, 5
• Venous pH and anion gap - follow to monitor resolution of acidosis (venous pH typically 0.03 units lower than arterial pH) 2, 3
• Potassium levels closely monitored - total body potassium is depleted despite potentially normal or elevated initial levels due to acidosis shifting potassium extracellularly 2, 5

Clinical Monitoring Parameters

• Continuous cardiac monitoring in severe DKA to detect arrhythmias early from electrolyte shifts 2
• Fluid input/output, hemodynamic parameters, and clinical examination to assess progress with fluid replacement 2
• Mental status changes - monitor for cerebral edema, particularly in children (occurs in 0.7-1.0% of pediatric DKA cases) 2

Identification of Precipitating Causes

Common Precipitants to Investigate

• Infections - most common precipitant; obtain cultures from urine, blood, throat, and other sites as indicated 1, 3, 6
• New diagnosis of diabetes - 20-30% of DKA cases present as initial manifestation 7, 6
• Insulin nonadherence or omission - common precipitant requiring patient education 6
• Myocardial infarction - search for acute coronary syndrome 1, 2
• Stroke - evaluate for cerebrovascular events 1, 2
• SGLT2 inhibitor use - can cause euglycemic DKA with normal or mildly elevated glucose; discontinue 3-4 days before surgery 2, 3, 4

Critical Pitfall: Euglycemic DKA

Clinicians must recognize that SGLT2 inhibitors can cause DKA with glucose levels <250 mg/dL or even normal glucose. 2, 3, 4 The traditional diagnostic triad should not rely solely on hyperglycemia - focus on ketosis and metabolic acidosis. 4

Resolution Criteria Before Transition

Laboratory Parameters Confirming DKA Resolution

• Glucose <200 mg/dL 2, 3, 5
• Serum bicarbonate ≥18 mEq/L 2, 3, 5
• Venous pH >7.3 2, 3, 5
• Anion gap ≤12 mEq/L 2, 3, 5

All four criteria must be met before transitioning from intravenous to subcutaneous insulin. 2, 3, 5

Special Monitoring Considerations

Corrected Sodium Calculation

Serum sodium should be corrected for hyperglycemia: add 1.6 mEq/L to measured sodium for every 100 mg/dL glucose above 100 mg/dL. 1 This guides appropriate fluid selection during resuscitation.

Osmolality Changes

Induced change in serum osmolality should not exceed 3 mOsm/kg/h to prevent cerebral edema. 2 Calculate osmolality serially to ensure gradual correction.