Hyperosmolar Syndrome

Description

• Results from a relative insulin deficiency in the undiagnosed or untreated diabetic
• Sustained hyperglycemia creates an osmotic diuresis and dehydration:
  • Extracellular space maintained by the osmotic gradient at the expense of the intracellular space
  • Eventually profound intracellular dehydration occurs
• Total body deficits of H₂O, Na⁺, Cl⁻, K⁻, PO₄⁻, Ca²⁺, and Mg²⁺
• In contrast to diabetic ketoacidosis (DKA), severe ketoacidosis does not occur:
  • Circulating insulin levels are higher
  • The elevation of insulin counter-regulatory hormones is less marked
  • The hyperosmolar state itself inhibits lipolysis (the release of free fatty acids) and subsequent generation of keto acids

• Most commonly seen in elderly type II diabetics who experience a stressful illness that precipitates worsening hyperglycemia and reduced renal function
• In the elderly, 30–40% of cases are associated with the initial presentation of diabetes

Etiology

• Hyperosmolar state precipitated by factors that:
  • Impair peripheral insulin action
  • Increase endogenous or exogenous glucose
  • Decrease patient's ability to replace fluid loss
• Infection (esp pneumonia and UTI) most common precipitating factor
• Other precipitating causes include:
  • Inadequate therapy/medication omission
  • Sepsis
  • Medications/drugs:
    • Diuretics
    • β-blockers
    • Calcium channel blockers
    • Atypical antipsychotics
    • Corticosteroids
    • Sympathomimetics
    • Phenytoin
    • Cimetidine
    • Amphetamines
    • Ethanol
  • Myocardial infarction
  • CVA
  • Renal failure
  • Heat stroke
  • Pancreatitis
  • Appendicitis
  • Intestinal obstruction
  • Endocrine disorders
  • Pregnancy
  • Trauma
  • Burns