Adrenal Insufficiency (Addison’s)

Causes:

• Primary: Autoimmune (idiopathic), infection (TB, fungal, CMV, Cryptococcus, toxoplasmosis, pneumocystis), surgical excision, trauma, hypotension, bilateral hemorrhage of adrenals (in disseminated meningococcal infection “Waterhouse-Friderichsen synd” + anticoagulation), adrenal dysgenesis, metastatic ca
• Secondary: more common: due to suppression of HPA axis by prolonged admin of exogenous steroids (> 3 wks), pituitary adenoma\craniopharyngioma

 

Clinical presentation:

1. Features seen only in primary:

• ↑ CRH-> ACTH+MSH release -> hyperpigmentation of skin and mucus membranes
• ↓ Aldosterone -> hyponatremia + hyperkalemia, met acidosis, ↓GFR and ↑BUN, hypotension, salt craving, ↓renal perfusion, shock, syncope

2. Features shared by all pts:

• Due to ↓ cortisol
• Mental sx: lethargy, confusion, psychosis
• GI sx: anorexia, wt loss, N\V, abdominal pain
• Hypoglycemia (cortisol is a gluconeogenic hormone)

 

Diagnosis:

• Best screening test\most specific: cosyntropin (synthetic ACTH) stimulation test: give cosyntropin IV (250 mg) -> check cortisol response after 1 hr -> normally cortisol ↑ (above 18.5 μg\dL)
• Gold standard: insulin tolerance test (insulin induced hypoglycemia): give insulin IV (.1-.15 units\kg) -> check cortisol during symptomatic hypoglycemia -> normally cortisol ↑ (above 18 μg\dL)
  • Contraindications: CAD, seizures, age >60

 

Treatment:

• Based on cause
• Hydrocortisone 10-12.5 mg\m²\day (also used in acute adrenal insuff)
• Mineralocorticoid (fludocortisterone) .05-.2 mg\m²\day -> only in primary

 

 

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Download the PDF version: here

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References:

• Kaplan step 2 videos and lecture notes
• Step up to medicine
• Master the boards