What are the pathophysiological changes affecting the metabolic / endocrine system that occur after brain death?

Endocrine & Metabolic System
  • Failure of hypothalamic-pituitary axis due to ischaemia with:
    • Impairment of temperature regulation
    • ADH depletion:
      • Diabetes insipidus (DI) which occurs in up to 65% of organ donors
      • Characterised by diuresis, hypovolaemia, plasma hyperosmolality and hypernatremia
    • ACTH depletion:
      • Reductions in cortisol production are unrelated to the degree of hypotension but may impair the stress response
    • TSH depletion:
      • Reductions in the circulating levels of tri-iodothyronine (T3) and thyroxine (T4)
  • Insulin depletion:
    • Contributes to the development of hyperglycemia
    • Aggravated by
      • Administration of large volumes of glucose containing fluids, if used to treat hypernatremia
      • Increased levels of catecholamines
  • Active inflammatory response commonly occurs due to:
    • Inflammatory mediators released from damaged brain
    • Generalized ischaemia– reperfusion (IR) injury
    • Metabolic changes at the time of the catecholamine storm