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
Download the PDF version: here
References:
- Kaplan step 2 videos and lecture notes
- Step up to medicine
- Master the boards
