Adrenal Pharmacology Flashcards Preview

Endo/Repro > Adrenal Pharmacology > Flashcards

Flashcards in Adrenal Pharmacology Deck (20):

Cortisol and Cortisone in CNS, muscle, liver, adipose

Cortisone --(11beta-hydroxylase 1)-> cortisol


Cortisol and Cortisone in kidney and colon

Cortisol --(11beta-hydroxylase 2)-> cortisone


Basal cortisol levels?

limited utility because of oscillating patterns and circadian rhythm pattern


ACTH stimulation test for diagnosing hypocortisolism

Addison's disease, iatrogenic withdrawal from glucocorticoids
Short Test - give small dose, check cortisol levels 1 hour later
Long Test - give large dose, check at intervals
- Addison's disease (primary) -> cortisol reduced at all timepoints
- Secondary disease -> delayed response


5 Tests to establish hypercortisolism

1. 24 hr urine cortisol (high cortisol confirms hypercortisolism)
2. Late night salivary (>2 tests --> loss of pattern indicative of Cushings)
3. Special populations (pregnancy, epilepsy)
4. Once its established --> baseline ACTH (low ACTH indicates independent disease, high ACTH indicates dependent disease)
5. Dex Test


Dexamethasone Challenge Test

1. Low dose -> failure to suppress cortisol after dose of dexamethasone (loss of negative feedback) -> confirms
- if cortisol is lower than normal, axis is working and Cushing is ruled out
2. High dose -> pituitary adenoma will show some reduction to high dex, ectopic tissue tumor will NOT


Cushing syndrome caused by adrenal tumor

Low dose test --> no change
ACTH level --> low
High dose test --> not needed


Cushing syndrome caused by ectopic ACTH tumor

Low dose test --> no change
ACTH level --> high
High dose test --> no change


Cushing syndrome caused by pituitary tumor

Low dose test --> no changed
High dose test --> normal suppression


Less Used diagnostic test

CRH/F stimulation test
- CRH stimulation used to distinguish Cushings from ectopic ACTH tumor
- Cushings will respond, ectopic tumors will not
- administer CRH --> ACTH/cortisol increase


Glucocorticoid effects

CV -> positive iontropic, increase BP (Na/H2O retention -> some mineralocorticoid activity)
CNS -> lowers seizure threshold, behavioral
GI -> increase acid, suppress immune, decrease Ca absorption
Bone -> direct inhibition of osteoclasts, stim PTH
Muscle -> hypokalemia, muscle wasting
Heme -> inhibits extravasation, suppress lymphocytes


Therapeutic Uses of Glucocorticoids

substitution and replacement of adrenal insufficiency......and many more!
- anti-inflammatory
- immunosuppressants
- anti-allergic


Natural vs. Synthetic

Synthetic are higher potency, less protein bound, and longer half-life
Cortisol has equal gluco and mineral activity
Prednisone, methylprednisone, dexa have all gluc activity
Fludrocortisone has mineral activity
* Addition of side chains enhance the potency


Active vs Inactive Cortisol

Cortisol (Prednisolone) is reduced and active
Cortisone (Prednisone) is oxidized and inactive
- prednisione gets activated in liver by 11beta-hydroxylase


Substitution/Replacement of adrenal insufficiency

Acute Adrenal Insufficiency -> sudden stop in glucocorticoids meds (IV Cortisol)
Chronic Primary Adrenal Insufficiency -> addisons (cortisol/fludrocortisone if needed)
Secondary Adrenal Insufficiency -> give cortisol
Congenital Adrenal Hyperplasia -> due to 21-hydroxylase deficiency -> give cortisol and fludrocortisone


Considerations when giving glucocorticoids

can produce toxicity
dose is determined by trial and error
high doses may be used in acute situations
gradual steroid withdrawal following chronic administration


Side Effects from Glucocorticoids

Hyperglycemia --> may need insulin
Peptic ulcer
Mineralocorticoid effects
- licorice slows down conversion of cortisol to cortisone


ACTH utility

it is a protein -> half-life of 10-15 minutes
- must be injected, mostly hydrolyzed by blood and tissue enzymes


Treatment of Cushings

surgery and support with glucocorticoids until recovery of ACTH function
- radiation for poor surgery candidates
- medical treatment


Medical Treatment of Cushings

Ketoconazole -> inhibits side-chain cleavage
- antifungal -> inhibit fungal cyto P450
- blocks glucocorticoid and androgen synthesis
Aminoglutethimide -> inhibits side-chain cleavage enzyme
Etomidate -> inhibits 11beta-hydroxylase
Metyrapone -> inhibits 11beta-hydroxylase in adrenal gland