Disorders of the Adrenal Gland (McLeod) Flashcards
Name the 4 zones of the adrenal gland going superficial to deep
- Zona glomerulosa (mineralcorticoids-aldosterone)
- Zona fasciculata (glucocorticoids-cortisol)
- Zona reticulata (androgens [DHEA])
- Medulla (catecholamines
What effect does aldosterone have on body fluid volume?
- Increased resorption of Na+ and water
- Increased excretion of K+ and H+
Glucocorticoid: effects
- Protects against hypoglycemia (Gluconeogenesis in the liver, proteolysis, lipolysis)
- Decrease insulin sensitivity
- Anti-inflammatory
- Maintain vascular responsiveness to NE/Epi
- Causes increase in GFR
When does serum total cortisol need to be drawn? why?
between 8am and 9am
-secretion is diurnal and highest in the morning
What value of total serum cortisol would make you think adrenal insufficency is very likely?
<3mg/dL = very likely adrenal sufficiency
24 Hour Urine for free cortisol: important points
- discard the first void
- record last voiding time
- refrigerate urine
Plasma ACTH: why is this test helpful
-Helps differentiate primary (adrenal) and secondary (pituitary) and tertiary (hypothalamic) cortisol imbalance
What else is drawn with serum ACTH and when is it drawn?
- AM
- with serum cortisol
ACTH stimulation test
- to see where the deficiency in cortisol is
- Give rapid/short acting cosyntropin IV (synthetic ACTH)
- Measure cortisol in the blood at 30-60 minutes
If cortisol level doubles during a ACTH stimulation test?
Adrenal gland is working
If cortisol level has a subnormal response during ACTH stimulation testing?
Adrenal Insufficeincy!
Describe the Dexamethasone suppresion test
- get baseline cortisol level
- give 1mg dexamethasone PO at 11PM
- Measure plasma cortisol levels at 8AM
Cushings Syndrome: diagnostics
- Elevated 24hr urine
- Midnight salivary cortisol elevated on 2 separate nights
- Dexamethasone suppresion test: no change in cortisol level
What imaging might you consider if you suspect an ectopic ACTH secreting tumor?
CXR to rule out lung mass
Pelvic ultrasound for ovarian mass
Medical management of Cushing’s Syndrome: Adrenal enzyme inhibitors
- Ketoconazole (can reduce cortisol at higher doses)
2. Metyrapone (inhibits cortisol synthesis)
Medical management of cushings: adrenolytic agents
Mitotane- “medical adrenalectomy” kills adrenocortical cells!
Most common cause of primary adrenal insufficiency
Autoimmune (Addison’s Disease) MC in the US
TB (worldwide most common)
Most common cause of secondary adrenal insufficiency
exogenous steroid use
also MC overall
Differentiate primary and secondary in regards to aldosterone and cortisol
In primary, both aldosterone and cortisol will be low
In secondary, aldosterone is intact but cortisol is low
Clinical signs of adrenal insufficiency
- hypotension
- hypoglycemia
- salt cravings
- hyperpigmentation*** (caused by elevated ACTH)
Adrenal insufficiency: Labs
- CMP: hyperkalemia, hypercalcemia, hyponatremia
- Eosinophilia
- Andi-adrenal antibodies
What are the 3 initial tests for adrenal insufficiency
- plasma ACTH
- plasma cortisol
- ACTH stimulation test
Adrenal crisis: Tx
- IV steroids
- Correct electrolyte abnormalities
- Dextrose to address hypoglycemia
- IV fluids/replace volume
How will someone present with Conn’s Syndrome/Primary hyperaldosteronism?
- HTN
- Low K+
- polyuria and polydipsia
