Outline the causes, consequences and management of adrenal insufficiency in the critically ill.
Causes of adrenal insufficiency in the critically ill can be categorised as primary (ie. diseases of the adrenal gland), secondary (interference with pituitary secretion of ACTH) and tertiary (interference with hypothalamic excretion of CRF).
Primary causes include autoimmune (may have vitiligo), haemorrhage (eg. with sepsis and/or anticoagulant therapy), emboli, sepsis and adrenal vein thrombosis.
Secondary causes include destruction of pituitary by tumour/cellular inflammation, infection, head trauma, and infarction.
Tertiary causes include abrupt cessation of high-dose corticosteroids, and any process that interferes with the hypothalamus (tumours, infiltration, irradiation). The stress of critical illness can unmask adrenal insufficiency in patients at risk
Consequences include shock (which may be refractory), abdominal tenderness, myalgias & arthralgias, nausea and vomiting, volume depletion, fever, and confusion. Electrolyte disturbances include hyperkalemia, and hyponatremia and hypoglycemia.
Management needs to commence before diagnosis is confirmed. Administration of corticosteroids (eg. hydrocortisone 100 mg or dexamethasone [4mg]; dexamethasone interferes least with cortisol assays associated with low or high dose short synacthen tests), fluid resuscitation (reversal of hypovolaemia and electrolyte abnormalities), and treatment for underlying causative and/or co-existing diseases (including sepsis) The diagnosis and treatment of stress induced impairment of the hypothalamic-pituitary–adrenal axis (functional adrenal insufficiency) remains controversial.
Adrenal insufficiency in critical illness is discussed elsewhere.
For the purposes of answering this question, I produce the following tables from the above-linked chapter:
Infarction due to arterial embolism
Infarction due to AAA
Postpartum pituitary necrosis
Menigococcal sepsis, purpura fulminans
Renal cell carcinoma
Etomidate (causes primary adrenal insufficiency)
Infiltrative systemic disease
Trauma is a major cause of adrenal insufficiency
Hypotension refractory to fluids
Decreased level of consciousness
Defects of other hormone systems (eg thyroid)
Management would have to be approached according tot he well-practiced answer algorithm:
- Attention to the ABCs;
- Airway assessment and control (in context of a decreased level of consciousness)
- Ventilation support (in context of metabolic acidosis)
- Circulatory support with vasopressors (in context of fluid-refractory shock)
- Routine investigations, partiuclarly EUCs CMPs and BSL (looking for hypoglycaemia hyponatremia and hyperkalemia)
- Specific investigations, such as a random cortisol level, and a short synacthen test
- Specific management, featuring corticosteroid supplementation with hydrocortisone
Oh's Intensive Care manual: Chapter 61 (pp. 660) Adrenocortical insufficiency in critical illness by Balasubramanian Venkatesh and Jeremy Cohen
Oelkers, Wolfgang. "Adrenal insufficiency." New England Journal of Medicine335.16 (1996): 1206-1212.
Marik, Paul E. "Mechanisms and clinical consequences of critical illness associated adrenal insufficiency." Current opinion in critical care 13.4 (2007): 363-369.
Cooper, Mark Stuart, and Paul Michael Stewart. "Adrenal insufficiency in critical illness." Journal of intensive care medicine 22.6 (2007): 348-362.