Expansion
Catabolic hormones rise, insulin falls, and salt and water are retained
Expansion
Hormones that rise
- Cortisol, up to fivefold, losing its diurnal rhythm
- Catecholamines
- Glucagon, growth hormone
- ACTH, antidiuretic hormone, aldosterone and renin
Hormones that fall or become ineffective
- Insulin secretion falls initially, then rises with marked insulin resistance
- Thyroid hormones (sick euthyroid pattern), testosterone
Consequences
- Hyperglycaemia (the “diabetes of injury”)
- Protein catabolism with muscle wasting and negative nitrogen balance
- Lipolysis
- Sodium and water retention with potassium loss
- Immunosuppression and a proinflammatory cytokine response
The magnitude is proportional to the severity of injury, and it is beneficial in evolutionary terms but harmful when prolonged.
Enhanced recovery protocols deliberately attenuate it: minimally invasive surgery, regional anaesthesia and good analgesia block afferent signalling, while avoiding prolonged fasting and giving preoperative carbohydrate reduces insulin resistance.