Is a patient with impaired renal function, severe hyperglycemia, and presence of ketones in Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS)?

Diagnostic Assessment: DKA vs HHS

This patient is in Diabetic Ketoacidosis (DKA), not pure HHS, though there may be overlapping features given the severe hyperglycemia and elevated osmolality.

Applying Diagnostic Criteria

Evidence for DKA Diagnosis

The patient meets all three required criteria for DKA 1:

• Hyperglycemia: Blood glucose 557 mg/dL (well above the 250 mg/dL threshold) 2, 1
• Metabolic acidosis: Bicarbonate 22 mEq/L is borderline (DKA requires <18 mEq/L for classic presentation), but the elevated anion gap of 18 strongly suggests metabolic acidosis 2
• Ketosis: Ketones 0.9 (assuming mmol/L for β-hydroxybutyrate) is elevated and confirms ketone body production 1

Why Not Pure HHS

While HHS typically presents with 2:

• Blood glucose >600 mg/dL (this patient has 557 mg/dL, close but not quite there)
• Serum osmolality >320 mOsm/kg (this patient has 311 mOsm/kg, below threshold)
• Minimal to absent ketones (this patient has measurable ketones at 0.9)
• pH >7.3 and bicarbonate >15 mEq/L (bicarbonate is 22 mEq/L, consistent with HHS range)

The presence of ketones (0.9) is the key distinguishing feature that tips the diagnosis toward DKA rather than pure HHS 2, 1. HHS is characterized by little or no ketosis, whereas this patient has documented ketonemia 3, 4.

Severity Classification

This appears to be mild to moderate DKA based on 1:

• Bicarbonate of 22 mEq/L (mild DKA: 15-18 mEq/L; this is actually higher, suggesting very mild or resolving acidosis)
• Anion gap of 18 (>10-12 mEq/L confirms metabolic acidosis) 2
• Need arterial pH to definitively classify severity (mild: pH 7.25-7.30; moderate: pH 7.00-7.24; severe: pH <7.00) 1

Critical Considerations

Overlapping Syndromes

DKA and HHS can coexist in the same patient 3, 4. This patient demonstrates features of both:

• Severe hyperglycemia and elevated osmolality (more typical of HHS)
• Documented ketosis with anion gap acidosis (diagnostic of DKA)

Renal Impairment Impact

The elevated creatinine (1.82) and reduced GFR (37) indicate significant renal dysfunction 2. This complicates the picture because:

• Impaired renal function can worsen acidosis and delay ketone clearance 2
• Fluid management must be carefully monitored to avoid volume overload 2
• Potassium replacement requires close monitoring given reduced renal clearance 2

Missing Critical Data

You must obtain an arterial or venous pH immediately to confirm the diagnosis and assess severity 2, 1. The bicarbonate of 22 mEq/L seems inconsistent with classic DKA unless:

• The patient is in very early/mild DKA
• There is a mixed acid-base disorder
• The patient has been partially treated or is compensating

Immediate Management Priorities

Based on the DKA diagnosis 2, 1:

1. Obtain arterial blood gas or venous pH immediately to confirm acidosis and guide treatment intensity 2, 1

2. Initiate IV fluid resuscitation: Start with 0.9% NaCl at 15-20 mL/kg/h (1-1.5 liters in first hour), but exercise caution given GFR of 37 2

3. Begin continuous IV insulin infusion: 0.1 units/kg/h after confirming potassium >3.3 mEq/L 2

4. Monitor potassium closely and replace aggressively: Add 20-30 mEq/L to IV fluids once renal function confirmed and urine output established, though adjust for existing renal impairment 2

5. Measure β-hydroxybutyrate specifically (if the 0.9 value is not already β-OHB) as this is the preferred method for monitoring DKA resolution, not nitroprusside-based tests 1

6. Search for precipitating cause: Obtain cultures, chest X-ray, and assess for infection, medication non-compliance, or other triggers 2

Resolution Criteria

DKA is resolved when 2, 1:

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

Do not stop insulin based on glucose normalization alone—continue insulin until acidosis and ketosis resolve, adding dextrose to IV fluids when glucose reaches 250 mg/dL 2, 1.