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:
Vascular aetiologiesInfarction due to arterial embolism Infarction due to AAA Postpartum pituitary necrosis InfectionSepsis Tuberculosis Histoplasmosis Cytomegalovirus Coccidiomycosis Menigococcal sepsis, purpura fulminans HIV Neoplastic invasionRenal cell carcinoma Adrenal carcinoma Breast carcinoma Lung (NSCLC) Malignant melanoma Pituitary tumour DrugsCorticosteroid withdrawal Etomidate (causes primary adrenal insufficiency) |
Infiltrative systemic diseaseAmyloid Congential causesAdrenal dysgenesis Autoimmune destructionAddisons's disease Traumatic destructionTrauma is a major cause of adrenal insufficiency Environmental factorsHypothermia |
Specific featuresHypotension refractory to fluids Eosinophilia Hypoglycaemia Hyponatremia Hyperkalemia Hyperpigmentation |
Non-specific featuresDecreased level of consciousness Defects of other hormone systems (eg thyroid) Normocytic anaemia Hyperdynamic circulation Metabolic acidosis Diarhroea Nausea Vomiting |
Management would have to be approached according tot he well-practiced answer algorithm:
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.