What is the formula to rule out Hyperosmolar Hyperglycemic State (HHS)?

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From the Guidelines

To rule out Hyperosmolar Hyperglycemic State (HHS), a patient must be assessed for severe hyperglycemia, hyperosmolality, and the absence of significant ketoacidosis, using the formula: 2(Na+) + glucose/18 + BUN/2.8 to calculate serum osmolality, as recommended in the hospital admission guidelines for diabetes 1. When evaluating a patient for HHS, it is crucial to obtain serum glucose, electrolytes, BUN, creatinine, and calculate serum osmolality. The diagnosis of HHS requires the presence of severe hyperglycemia (typically glucose >600 mg/dL), hyperosmolality (serum osmolality >320 mOsm/kg), and the absence of significant ketoacidosis.

  • Key criteria for HHS diagnosis include:
    • Severe hyperglycemia (glucose >600 mg/dL)
    • Hyperosmolality (serum osmolality >320 mOsm/kg)
    • Absence of significant ketoacidosis
  • Additional assessments should include:
    • Dehydration (often 8-12 liters deficit)
    • Altered mental status
    • Precipitating factors like infection or medication non-compliance The treatment of HHS focuses on fluid resuscitation, insulin therapy, electrolyte replacement, and addressing underlying causes, with the goal of reducing morbidity, mortality, and improving quality of life, as outlined in the guidelines for hospital admission for diabetes 1.

From the Research

Diagnostic Criteria for HHS

To rule out Hyperosmolar Hyperglycaemic State (HHS), the following criteria can be used:

  • Plasma glucose level >600 mg/dL or ≥30 mmol/L 2, 3
  • Increased effective plasma osmolality ≥320 mOsm/kg, calculated using [(2×Na+ ) + glucose+urea] 3, 4
  • Absence of significant ketonaemia (≤3.0 mmol/L) 3
  • Absence of significant acidosis (pH >7.3) and bicarbonate ≥15 mmol/L 3
  • Marked hypovolaemia 3, 4

Treatment and Management

Treatment guidelines for HHS recommend:

  • Aggressive volume-repletion of osmotic losses with intravenous (IV) 0.9% sodium chloride to restore circulating volume 3, 4
  • Fixed rate intravenous insulin infusion (FRIII) should be commenced once osmolality stops falling with fluid replacement unless there is ketonaemia 3
  • Glucose infusion (5% or 10%) should be started once glucose <14 mmol/L 3
  • Potassium replacement according to potassium levels 3
  • Identification and treatment of underlying precipitants 3, 4, 5

Resolution Criteria

HHS resolution criteria include:

  • Osmolality <300 mOsm/kg 3
  • Hypovolaemia corrected (urine output ≥0.5 ml/kg/h) 3
  • Cognitive status returned to pre-morbid state 3
  • Blood glucose <15 mmol/L 3

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Hyperosmolar Hyperglycemic State.

Emergency medicine clinics of North America, 2023

Research

Hyperosmolar hyperglycemic state.

Emergency medicine clinics of North America, 2005

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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