What is the management for a patient presenting with altered mental status and a urinalysis (UA) positive for ketones?

Management of Altered Mental Status with Ketonuria

This patient requires immediate evaluation for diabetic ketoacidosis (DKA), which is a life-threatening emergency that demands urgent laboratory confirmation, aggressive fluid resuscitation, continuous insulin infusion, and intensive monitoring—even if initial glucose is only mildly elevated or normal, as euglycemic DKA can occur. 1, 2

Immediate Diagnostic Workup

The presence of altered mental status with ketonuria is highly concerning for severe DKA and requires stat laboratory evaluation 1, 2:

• Obtain venous blood gas immediately to assess pH (DKA defined as pH <7.3) 2, 3
• Measure serum glucose, electrolytes (including sodium, potassium, chloride), BUN, creatinine, and calculate anion gap using [Na⁺] - ([Cl⁻] + [HCO₃⁻]) 2
• Direct measurement of β-hydroxybutyrate in blood is the preferred method for confirming ketosis—do not rely on urine ketones alone, as the nitroprusside method only measures acetoacetate and acetone, missing β-hydroxybutyrate which is the predominant ketoacid 2, 4
• Correct serum sodium for hyperglycemia by adding 1.6 mEq/L for every 100 mg/dL glucose above 100 mg/dL 1, 2
• Obtain cultures (blood, urine, throat) if infection suspected as this is a common precipitating factor 2, 5

Severity Classification Based on Mental Status

Altered mental status indicates at minimum moderate to severe DKA 2, 3:

• Moderate DKA: pH 7.00-7.24, bicarbonate 10-15 mEq/L, drowsy but arousable 3
• Severe DKA: pH <7.00, bicarbonate <10 mEq/L, stupor or coma—this requires ICU admission with central venous and arterial pressure monitoring 2, 3

Initial Management Protocol

Fluid Resuscitation (First Priority)

Begin aggressive isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour immediately to restore circulatory volume and tissue perfusion 2, 3:

• Total fluid replacement should correct estimated deficits within 24 hours 1
• Monitor carefully for fluid overload in patients with renal or cardiac compromise 1
• Change in serum osmolality should not exceed 3 mOsm/kg H₂O per hour 1

Potassium Management (Critical Before Insulin)

Check serum potassium before starting insulin 2:

• If K⁺ <3.3 mEq/L: Delay insulin and aggressively replace potassium first to prevent fatal cardiac arrhythmias 2
• If K⁺ 3.3-5.5 mEq/L: Add 20-30 mEq potassium per liter of IV fluid once adequate urine output confirmed 2, 3
• If K⁺ >5.5 mEq/L: Hold potassium replacement but recheck frequently 2

Insulin Therapy

Start continuous IV regular insulin infusion at 0.1 units/kg/hour (typically 5-7 units/hour in adults) without an initial bolus 1, 2:

• Target glucose decline of 50-75 mg/dL per hour 1, 2
• If glucose does not fall by 50 mg/dL in first hour, double the insulin infusion rate hourly until steady decline achieved 2
• When glucose reaches 200-250 mg/dL, add dextrose (5% dextrose with 0.45% saline) to IV fluids while continuing insulin infusion to clear ketones 2, 3

Monitoring During Treatment

Check blood glucose, electrolytes, BUN, creatinine, venous pH, and β-hydroxybutyrate every 2-4 hours 2:

• Venous pH adequately monitors acidosis resolution—repeated arterial blood gases are unnecessary 2
• Ketonemia takes longer to clear than hyperglycemia, so continue monitoring β-hydroxybutyrate even after glucose normalizes 1, 2

Resolution Criteria and Transition

DKA is resolved when all of the following are met 2:

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

Administer subcutaneous basal insulin 2-4 hours before stopping IV insulin to prevent rebound hyperglycemia and recurrent ketoacidosis 1, 2

Critical Pitfalls to Avoid

• Do not assume normal glucose excludes DKA—euglycemic DKA can occur, particularly with SGLT2 inhibitor use 5
• Do not use bicarbonate therapy unless pH <6.9, as studies show no benefit in mortality or resolution time 1, 2
• Do not rely on urine ketones for monitoring—they paradoxically worsen as β-hydroxybutyrate converts to acetoacetate during treatment 2
• Do not start insulin if potassium <3.3 mEq/L—this can precipitate fatal arrhythmias 2
• Monitor closely for cerebral edema, especially with overly aggressive fluid resuscitation 2

Identify and Treat Precipitating Cause

Common triggers requiring specific treatment 1, 2, 5:

• Infection (38.8% of cases)—obtain cultures and start antibiotics if indicated 6, 5
• Insulin omission (44.4% of cases)—requires psychological assessment and patient education 3, 6
• Myocardial infarction or stroke—obtain ECG and consider neuroimaging if indicated 1
• New diagnosis of diabetes 5