What are the diagnostic criteria and management of Hyperosmolar Hyperglycemic State (HHS)?

Diagnosis and Management of Hyperosmolar Hyperglycemic State (HHS)

Diagnostic Criteria for HHS

HHS is diagnosed when a patient presents with blood glucose ≥600 mg/dL, effective serum osmolality ≥320 mOsm/kg H₂O, arterial pH >7.3, serum bicarbonate >15 mEq/L, minimal or absent ketones in urine or serum, and altered mental status. 1

The complete diagnostic criteria include:

Parameter	HHS Criteria
Plasma glucose	≥600 mg/dL
Arterial pH	>7.3
Serum bicarbonate	>15 mEq/L
Urine ketones	Small/minimal
Serum ketones	Small/minimal
Effective serum osmolality	≥320 mOsm/kg H₂O
Anion gap	Variable
Mental status	Stupor/coma (typically altered)

The effective serum osmolality calculation is crucial for diagnosis:

• Formula: Effective serum osmolality = 2[measured Na⁺ (mEq/L)] + glucose (mg/dL)/18 1

Clinical Presentation

HHS differs from DKA in several key ways:

• Develops gradually over days (not hours like DKA)
• Results in extreme dehydration (100-220 mL/kg fluid losses) 2
• Severe hyperglycemia (typically >600 mg/dL)
• Minimal or absent ketosis
• Altered mental status due to extreme hyperosmolality
• Higher mortality rate compared to DKA 1, 3

Management Approach

Initial Resuscitation (0-60 minutes)

1. Fluid Replacement (Priority)

   • Begin with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour 1
   • Focus on restoring circulating volume before starting insulin 3, 2
   • Goal: Correct estimated fluid deficit within 24 hours 1

2. Insulin Therapy

   • Withhold insulin until fluid resuscitation has begun and glucose is no longer falling with IV fluids alone (unless ketonaemic) 3, 2
   • When initiated: 0.15 U/kg IV bolus, followed by continuous infusion at 0.1 U/kg/hour 1
   • Adjust to achieve glucose decrease of 50-75 mg/dL/hour 1

3. Electrolyte Management

   • Add potassium (20-30 mEq/L) once renal function is confirmed and serum potassium is known 1
   • Use 2/3 KCl and 1/3 KPO₄ for potassium replacement 1
   • Monitor and replenish magnesium, calcium, and phosphate as needed

Ongoing Management (1-24 hours)

1. Controlled Osmolality Reduction

   • Target osmolality reduction rate: 3-8 mOsm/kg/hour 1, 3, 2
   • Avoid rapid correction to prevent neurological complications
   • Switch to 0.45% saline after hemodynamic stability is achieved 4

2. Glucose Management

   • Add 5% or 10% dextrose infusion once glucose falls below 250-300 mg/dL 2, 4
   • Reduce insulin infusion rate when adding dextrose
   • Target blood glucose: 10-15 mmol/L (180-270 mg/dL) in first 24 hours 2

3. Monitoring Parameters

   • Vital signs and hemodynamic status hourly
   • Mental status assessment
   • Fluid intake/output
   • Electrolytes, glucose, BUN, creatinine every 2-4 hours
   • Calculate osmolality regularly to monitor treatment response 1, 3

Resolution Criteria

HHS is considered resolved when:

• Blood glucose <300 mg/dL
• Serum osmolality <315 mOsm/kg
• Patient is alert and able to ingest liquids 1
• Hypovolemia corrected (urine output ≥0.5 mL/kg/h)
• Cognitive status returned to pre-morbid state 2

Common Pitfalls and Complications

1. Treatment Pitfalls

   • Failing to recognize mixed DKA/HHS presentations
   • Starting insulin before adequate fluid resuscitation
   • Rapid correction of osmolality
   • Inadequate monitoring of electrolytes 1

2. Complications

   • Cerebral edema from rapid osmolality changes 3, 5
   • Central pontine myelinolysis 3
   • Hypoglycemia and hypokalemia during treatment
   • Thromboembolism (consider prophylaxis) 1, 2
   • Multiorgan failure including renal failure, respiratory distress, rhabdomyolysis, heart failure 5

Special Considerations

• Elderly patients and those with cardiac or renal disease require more cautious fluid management 1
• Identify and treat precipitating factors (infection, medication non-adherence, stroke, etc.)
• Involve diabetes specialist team as soon as possible 3
• After recovery, many patients may not require long-term insulin therapy 4

Patient Education for Prevention

• Never suspend insulin during illnesses
• Recognize early symptoms of hyperglycemic crisis
• Know when to seek medical attention
• Maintain regular glucose monitoring, especially during illness or stress 1