Disorders of the Adrenal Gland Flashcards
What is cushing syndrome? What usually causes it?
Cushing syndrome refers to the signs and symptoms of excess cortisol most commonly caused by exogenous glucocorticoid therapy.
Besides exogenous glucocorticoid therapy, what can cause cushing syndrome?
- Pituitary adenomas (Causes cushing disease; excess ACTH from the pituitary leads to bilateral adrenal hyperplasia)
- adrenocortical tumors
- ectopic ACTH production (seen with small-cell carcinoma of the lung and bronchial carcinoid tumors
What is the classic clinical picture for cushing syndrome?
- Hypertension
- central obesity
- weight gain
- moon facies (rounded appearance of face due to small fat deposits)
- insulin resistance
- thin skin/purple striae
- osteoporosis
- buffalo hump
- amenorrhea
Will Cortisol and ACTH be up or down in the following conditions:
- Primary hypercortisolism (cortisol-producing tumor)
- Pituitary hypersecretion of ACTH (Cushing)
- Primary adrenal insufficiency (Addison disease)
- Secondary adrenal insufficiency
- Primary hypercortisolism (cortisol-producing tumor): Cortisol up, ACTH down
- Pituitary hypersecretion of ACTH (Cushing): Cortisol up and ACTH up
- Primary adrenal insufficiency (Addison disease): Cortisol down, ACTH up
- Secondary adrenal insufficiency Cortisol down and ACTH down
How do we screen for cushings?
The initial screen is the overnight dexamethasone (a cortisol analog) suppression test. In normal individuals, dexamethasone suppresses ACTH release from the pituitary and results in decreased cortisol release. In cushing syndrome, cortisol levels fail to be suppressed. A 24 hour urinary free cortisol level is the gold standard diagnostic test.
Following this, ACTH levels are assessed. High ACTH levels indicate that the cortisol being high is linked to the ACTH being high. You do a high dose dexamethasone suppression test.
The point of this is to distinguish pituitary cushings from an ectopic ACTH producing tumor causing cushings. Cortisol after the high dose dexamethasone would be suppressed in pituitary Cushings, but not in the tumor.
What in the hell is Conn Syndrome?
Conn syndrome, or primary hyperaldosteronism, is where excessive aldosterone is produced, typically by adrenocortical adenomas, carcinomas, or hyperplasia of the zona glomerulosa.
What happens with too much aldosterone?
Increased sodium resorption and potassium excretion.
How does Conn Syndrome present and why?
Sodium and water retntion causes hypertension.
Severe hypokalemia causes symptoms of muscle weakness and can cause arrhythmias
Excess aldosterone causes increased Na+ reabsorption and increased K+ and H+ secretion, leading to mild hypernatremia, hypokalemia, and metabolic alkalosis.
How do we test for Conn syndrome?
- Serum chem - Mildly increased Na+ and decreased K+ and increased bicarb
- Aldosterone-to-renin ratio: ARR > 20 is diagnostic
- Sodium suppression test - Sodium load patient and then measure for appropriate aldosterone suppression. Infusion of saline normally decreases aldosterone levels but does not do so in Conn Syndrome
Treating Conn Syndrome
Surgery for that tumor. If you can’t, use Spironolactone to inhibit aldosterone on the kidneys along with other anti-hypertensives to manage the high blood pressure
What is Addison disease and what causes it?
Results from adrenal gland failure and is most commonly due to autoimmune destruction of the adrenal glands.
What kind of infections can cause Addison Disease?
- TB
- CMV
- Histoplasmosis
- disseminated meningococcemia as seen in Waterhouse Friderichsen syndrome
Besides infections, what can cause Addison Disease
- Vascular disorders like infarctions
- cancer
- drugs (ketoconazole, rifampin)
- Infiltrative diseases (hemochromatosis, amyloidosis, sarcoidosis)
How does Addison Disease present?
Most commonly manifests as weakness, fatigue, anorexia, nausea/vomiting, orthostasis, hyponatremia, and hypoglycemia, all stemming from decreased cortisol and mineralcorticoid deficiency.
Increased ACTH in primary adrenal insufficiency leads to skin hyperpigmentation (due to increased MSH) and hyperkalemia; decreased aldosterone leads to hypotension (due to salt loss), weakness, and hypoperfusion.
What is ACTH stimulating testing?
We use this as a diagnostic technique for Addison Disease.
Administer ACTH IV to stimulate cortisol. Normally, the adrenal gland increases its production of cortisol in response to ACTH. In primary and chronic secondary adrenal insufficiency, cortisol production does not increase considerably when ACTH is given.
