In our #AMreport today at @WCHospital, we reviewed a case of primary adrenal insufficiency. Although rare, we discussed the importance in treating suspected cases of primary adrenal insufficiency early to mitigate mortality risk from cardiovascular collapse and other complications.
What causes it?How do I diagnose? How do I treat?
1.What Causes It?
The most common cause of primary adrenal insufficiency is autoimmune adrenalitis with about 70-90% of cases.
Other causes include:
- Infectious (eg. TB, CMV, fungal infections & other OIs from HIV such as MAC)
- Bilateral adrenal hemorrhage (eg.Waterhouse-Friderichsen syndrome classically associated with meningococcemia)
- Drugs that inhibit cortisol synthesis in patients with reduced pituitary/adrenal reserve (eg. ketoconazole, fluconazole)
2.How do I diagnose it?
The diagnosis of primary adrenal insufficiency is made based on the following:
- Inappropriately low cortisol secretion.
- Determining whether the cortisol secretion is dependent or independent on ACTH.
- Concurrent mineralocorticoid deficiency.
- ACTH stimulation test steps
- Baseline cortisol at 0 mins → ACTH 250 mcg IV given after first blood drawn.
- Measure cortisol levels at 30,60 minutes to determine if change in level.
- A normal response to the high-dose (250 mcg as an intravenous [IV] bolus)
- ACTH stim testis a rise in serum cortisol concentration after either 30 or 60 minutes to a peak of ≥18 to 20 mcg/dL (500 to 550 nmol/L)
3. How do I treat?
Acute treatment: dexamethasone 4 mg Q6H IV.
- The rationale is that most labs that measure cortisol levels use an assay that cannot differentiate between prednisone/ hydrocortisone from “true” cortisol which in turn can affect the reliability of your stimulation test.
- Glucocorticoid therapy (hydrocortisone, prednisone or dexamethasone)
- Hydrocortisone is preferred since it has a a much shorter half-life and consequently can be titrated to mimic diurnal cortisol secretion.
- Mineralocorticoid therapy (Fludrocortisone 0.05-0.1mg/d)
- Only cases of primary adrenal insufficiency.