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- High at 4:30 in the morning to compensate for insulin burst. Cortisol makes the body more resistant to insulin & causes the liver to release more glucose leading to hyperglycemia. Cortisol alo affects thickness of blood, increasing chances of heart attack and stroke.
- Lowest at midnight, leading to higher incidence of suicide attempts at this time.
Feedback loop of CRH and ACTH
CRH from the hypothalamus (during times of extreme stress) stimulates the anterior pituitary to release ACTH which will stimulate the adrenals to produc cortisol. Rising cortisol levels will then inhibit production of both ACTH and CRH. ACTH can also feedback on CRH production.
Layers of adrenal glands
- Cortex - Where adosterone, cortisol and androgens are produced (steroid hormones). Regulated by ACTH.
- Medulla - Middle nerve organ layer of adrenals. Makes epinephrine and norepinephrine in response to nerve impulses.
Exogenous glucocorticoids, ACTH-producing pituitary tumor, cortisol-secreting adrenal adenoma, ectopic CRH or ACTH producing tumors
- Moon facies
- cervicodorsal fat pad "buffalo hump"
Test for Cushing's
Dexamethasone suppression test
Most common cause is glucocorticoids that get stopped abruptly.
Hypothalamic pituitary adrenal suppression (HPA)
- Presumed in pts who...
- received a glucocorticoid dose equal to more than 20mg prednisone a day for more than 3 weeks
- received an evening dose of prednisone for more than a few weeks (because you make the least amount of cortisol at night)
- Pts with a cushingoid appearance
Primary adrenal insufficiency
Due to adrenal glands failing which will also knock out DHEA-S and aldosterone. Aldosterone controls Na and K. Need to replace cortisol and aldosterone. Florinef treats K by acting on aldosterone.
Primary adrenal insufficiency symptoms
- low Na
- High K
- Low cortisol
- High ACTH
Secondary adrenal insufficiency
Due to pituitary failure in making ACTH (withdrawal from prednisone). Need to replace cortisol, aldosterone is fine.
Secondary adrenal insufficiency symptoms
- Slightly low Na
- Low cortisol
- Low ACTH
Adrenal (Addisonian) Crisis symptoms
- Volume depletion
- Hypotension and shock
- fever (99-100 degrees)
- Hypoglycemia (low cortisol makes insulin work better since it's antagonistic)
Adrenal insufficiency test
Corticotropin (ACTH) stimulation test - if it doesn't increase by more than 25 then they are insufficient
- hydrocortisone for adrenal crisis
- Cortisol injections for cortisol deficiency
Adrenal medulla produces too much epinephrine and norepinephrine (adrenaline and noradrenaline) - these are catecholamines. These are also produced during stress response.
- The 5 P's
- Pressure (HTN)
- Pain (episodic headache)
- The bolded middle 3 are the classic triad. If they have the triad, they also need to have HTN to diagnose.
- 24-hour urine catecholamines on a non-stressful day
- Positive if there is a > 2-fold increase
- Can also do plasma metanephrines after, but it gets false-positives frequently.