Adrenal insufficiency

OVERVIEW

Types:

• primary, secondary and tertiary + acute/chronic

Primary = Addison’s

• destruction of > 90% of adrenal glands
• rare
• causes: autoimmune destruction, haemorrhage, tumour (breast and melanoma), infection (Tb, HIV, meningococcemia, purpura fulminans) or inflammatory process
• loss of mineralocorticoid and glucocorticoid activity

Secondary

• insufficient production of ACTH
• rare
• mineralocorticoid function intact
• causes: destruction or dysfunction of the pituitary

Tertiary/Iatrogenic/Relative

• suppression of HPA axis over time
• most common
• cause: administration of exogenous glucocorticoids
• mechanism: chronic ACTH suppression -> adrenal atrophy

ADRENAL CRISIS

• concurrent illness, surgery, failure to take medications
• GI: abdominal pain, vomiting and diarrhoea
• CVS: dehydration, hypotension, refractory shock, poor response to inotropes/pressors
• fever
• confusion

CHRONIC ADRENAL INSUFFICIENCY

• GENERAL: weight loss, arthralgia, myalgia
• CNS: fatigue, anorexia, mood change
• CVS: postural hypotension, syncope, salt craving
• SKIN: pigmentation, vitiligo
• ELECTROLYTES: hypoglycaemia, hyponatraemia, hyperkalaemia, increased urea

INVESTIGATIONS

Diagnosis:

• plasma cortisol level < 80mmol/L
• short synacthen test: 250mcg (normal response = cortisol > 525mmol/L)

Other

• low glucose
• low Na+
• hypo-osmolar
• raised K+
• raised U and Cr
• raised Ca2+ (primary only)
• eosinophilia

MANAGEMENT

• fluid resuscitation
• reversal of electrolyte abnormalities
• high dose hydrocortisone (100mg IV Q6 hrly)
• mineralocorticoid replacement (fludrocortisone PO 0.1mg Q6 hrly) – don’t often use this acutely as with > 50mg of hydrocortisone you get a mineralocorticoid effect

References and links

LITFL

• CCC – Steroid conversion
• CCC – Corticosteroids Overview
• CCC – Steroids and Septic Shock Literature Summaries
• CCC – Corticosteroid therapy for shock
• Basic Science – Pharm 101: Corticosteroids

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