Adrenal disorders Flashcards
Adrenal insufficiency
Adrenal crisis
Work-up: biochem/metabolic panel, serum cortisol, plasma ACTH (corticotropin), plasma renin activity or concentration, aldosterone level
Treatment: IV saline and glucocorticoids (hydrocortisone, dexamethasone, methylprednisolone) during periods of surgery / acute stress
Adrenal insufficiency - testing
Cortisol levels:
- morning cortisol (6-8am) normal range is 330-550.
Patients w adrenal insuff may have normal AM cortisol, so need to do ACTH testing if suspicion warrants.
ACTH test
- It is inexpensive and safe. No fasting required. No SE’s. Allergy is rare. Best done in the morn (i.e. 8am). Normal response to synacthen excludes both 1’ and 2’ adrenal insuff
- administration of 250mcg IV cosyntropin (has same biologic potency of native ACTH)
- measure cortisol at baseline, 30mins, 60mins.
- can take basline ACTH levels also
- A value of >500nmol/L before or after ACTH injection is considered normal cortisol level. A rise in cortisol of ? >200nmol/L is normal (refer to endocrine manual)
- OCP (pill) increases CBG (cortisol binding globulin), which increases cortisol levels
- nephrotic syndrome –> less CBG –> lower cortisol response to ACTH
There is also CRH stimulation testing available (secondary vs tertiary adrenal insuff)
Primary adrenal insufficiency (Addison’s disease)
- low AM cortisol (6-8am), lack of elevation with stimulation test
- increased plasma ACTH (corticotropin) levels
Secondary adrenal insuff (pituitary corticotrophs disorder/failure)
- low plasma ACTH levels
- normal or subnormal cortisol elevation with ACTH stimulation test (as chronically low ACTH leads to adrenal atrophy)
Tertiary adrenal insuff (hypothalamic disorder)
- CRH (corticotropin releasing hormone) deficiency; subsequent ACTH deficiency
steroids - glucocorticoids
Glucocorticoids
- Prednisone and prednisolone have similar systemic bioavailability
- methylpred has variable GI absorption (50-90% bioavailability)
