Adrenal/Pituitary/DI Flashcards
What are the components of each adrenal gland?
Cortex and medulla
What does the cortex of the adrenal gland synthesize?
Glucocorticoids, mineralocorticoids, and androgens
What hormone does the hypothalamus send to the anterior pituitary in adrenal gland dysfunction?
Corticotropin-releasing hormone (CRH)
What does ACTH stimulate in the adrenal cortex?
Production of cortisol
What does cortisol facilitate in the adrenal medulla?
Conversion of NE to EPI
What effects does cortisol induce in terms of glucose metabolism?
Hyperglycemia, gluconeogenesis, inhibition of glucose uptake by cells
What are the combined effects of cortisol and aldosterone?
Sodium retention and K+ excretion
What are pheochromocytomas?
Catecholamine-secreting tumors
Where do pheochromocytomas arise from?
Chromaffin cells of sympathoadrenal system
What can uncontrolled catecholamine release from pheochromocytomas result in?
Malignant HTN, CVA, MI
What percentage of pheochromocytomas are inherited?
10%
Where do 80% of pheochromocytomas occur?
Adrenal medulla
How do malignant pheochromocytomas spread?
Through venous & lymph systems
What is the typical secretion ratio of NE:EPI in most pheochromocytomas?
85:15
What do some pheochromocytomas secrete at higher levels?
EPI and dopamine
What are the symptoms of pheochromocytoma?
h/a, pallor, sweating, palpitations, orthostatic HoTN
How is pheochromocytoma diagnosed?
24h urine collection for metanephrines and catecholamines
How can the tumor in pheochromocytoma be localized?
CT & MRI imaging, MIBG scintigraphy
What is the preoperative treatment for Pheochromocytoma?
α blockade with drugs like Phenoxybenzamine
Why is α blockade important in Pheochromocytoma preop?
To lower BP, decrease intravascular volume, prevent hypertensive episodes
What happens if tachycardia occurs after α blockade in Pheochromocytoma?
Treat with beta-blockers
Why should nonselective beta-blockers not be given before α blockers in Pheochromocytoma?
May lead to unopposed α agonism and hypertensive crises
Besides alpha blockers, what other drug class is used to control hypertension in Pheochromocytoma?
CCBs
What are the 2 forms of Hypercortisolism (Cushing Syndrome)?
ACTH dependent and ACTH independent
What stimulates the adrenal cortex to produce excessive amounts of cortisol in ACTH-dependent Cushing’s syndrome?
Inappropriately high plasma ACTH
What is acute ectopic ACTH syndrome often associated with?
Small cell lung carcinoma
What is the most common cause of ACTH-independent Cushing syndrome?
Benign or malignant adrenocortical tumors
What are the symptoms of hypercortisolism?
Sudden weight gain, central obesity, moon face, ecchymoses, HTN, glucose intolerance, muscle wasting, depression, insomnia
How is Cushing’s syndrome diagnosed?
24 hr urine cortisol
How can you determine if Cushing’s is ACTH dependent or independent?
Plasma ACTH measurements
What test distinguishes Cushing’s from ectopic ACTH syndrome?
High-dose dexamethasone suppression test
Are imaging procedures useful for determining adrenal cortex function in Cushing’s syndrome?
No
What is the treatment of choice for Cushing Syndrome if a microadenoma is resectable?
Transsphenoidal microadenomectomy
What is an alternative treatment option for Cushing Syndrome if a microadenoma is not resectable?
85-90% resection of the anterior pituitary
When is pituitary irradiation and bilateral total adrenalectomy necessary in patients with Cushing Syndrome?
In some cases
What is the treatment for adrenal adenoma or carcinoma in Cushing Syndrome?
Surgical removal of the adrenal gland
What should be evaluated and treated preoperatively in patients with Cushing Syndrome?
Blood pressure, electrolyte imbalance, blood glucose
What should be considered in positioning due to long-term effects in Cushing Syndrome patients?
Osteoporosis
What is primary hyperaldosteronism?
Excess aldosterone from tumor
What can primary hyperaldosteronism be occasionally associated with?
Pheochromocytoma, hyperparathyroidism, acromegaly
What is secondary hyperaldosteronism characterized by?
Increased renin stimulating aldosterone release
What are some symptoms of hyperaldosteronism?
HTN, hypokalemia, metabolic alkalosis
What is a highly suggestive sign of hyperaldosteronism?
Spontaneous hypokalemia with systemic hypertension
How does plasma renin activity differ between primary and secondary hyperaldosteronism?
Primary: suppressed; Secondary: high
What can long-term ingestion of licorice lead to?
Features mimicking hyperaldosteronism (HTN, hypokalemia, RAAS suppression)
What are the treatment options for hyperaldosteronism?
Spironolactone, K+ replacement, antihypertensives, diuretics, tumor removal, adrenalectomy
What does hyperkalemia in the absence of renal insufficiency suggest?
Hypoaldosteronism
How can hyperkalemia be enhanced?
By hyperglycemia
What type of metabolic acidosis is common in hypoaldosteronism?
Hyperchloremic
What symptoms may be present in hypoaldosteronism besides hyperkalemia?
Heart block, orthostatic HoTN, hyponatremia
In what conditions does hyporeninemic hypoaldosteronism typically occur?
In patients >45 with CRF or DM
What is a reversible cause of hypoaldosteronism induced by a medication?
Indomethacin-induced prostaglandin deficiency
What is the treatment for hypoaldosteronism?
Liberal sodium intake, fludrocortisone
What are the 2 types of Adrenal Insufficiency?
Primary and secondary
What is the most common cause of primary Adrenal Insufficiency?
Autoimmune adrenal destruction
In primary Adrenal Insufficiency, how much of the adrenal glands must be involved before signs appear?
> 90%
What is the main hormone deficiency in secondary Adrenal Insufficiency?
Only glucocorticoid
What is the most common cause of secondary Adrenal Insufficiency?
Iatrogenic (e.g., pituitary surgery, synthetic glucocorticoids)
What is a clinical difference between primary and secondary Adrenal Insufficiency?
Cutaneous hyperpigmentation is lacking in secondary AI
What is the diagnostic criteria for adrenal insufficiency?
Baseline cortisol < 20 μg/dL and remains <20 μg/dL after ACTH stimulation
How is absolute adrenal insufficiency characterized?
Low baseline cortisol level and positive ACTH stimulation test result
How is relative adrenal insufficiency indicated?
Higher baseline cortisol level but positive ACTH stimulation test result
What is the treatment for adrenal insufficiency?
Steroids
Where are the parathyroid glands located?
Behind upper & lower poles of thyroid gland
What hormone do the parathyroid glands produce?
PTH
How is PTH released into circulation?
Negative feedback dependent on plasma calcium level
What stimulates the release of PTH?
Hypocalcemia
How does hypercalcemia affect PTH?
Suppresses both synthesis and release
What is the role of PTH in maintaining plasma calcium levels?
Promoting calcium movement in GI tract, renal tubules, and bone
What is hyperparathyroidism?
Increased PTH secretion
How is hyperparathyroidism classified?
Primary, secondary, or ectopic
What are the causes of primary hyperparathyroidism?
Adenoma, carcinoma, hyperplasia
What are the symptoms of hyperparathyroidism?
Sedation, n/v, weakness, sensation changes, polyuria, renal stones, PUD, cardiac disturbances
How is hyperparathyroidism diagnosed?
Plasma calcium, 24 hr urinary calcium
What is the treatment for hyperparathyroidism?
Surgical removal of abnormal gland portions
What is secondary hyperparathyroidism?
Compensatory response to counteract a separate disease process causing hypocalcemia
Why does secondary hyperparathyroidism seldom produce hypercalcemia?
Adaptive response
How is secondary hyperparathyroidism treated?
Controlling underlying disease, normalizing serum phosphate concentrations
What is hypoparathyroidism?
Deficient PTH or tissue resistance
What is pseudohypoparathyroidism?
PTH adequate, kidney resistance
How is hypoparathyroidism diagnosed?
Hypocalcemia, ↓PTH, ↑phosphate
What are symptoms of chronic hypocalcemia?
Fatigue, cramps, prolonged QT
What is the most common cause of chronic hypocalcemia?
CRF
How is hypoparathyroidism treated?
Calcium replacement, Vitamin D
Where is the pituitary gland located?
Sella turcica at the base of the brain
What are the two parts that the pituitary gland consists of?
Anterior pituitary & posterior pituitary
What hormones does the anterior pituitary secrete?
6 hormones under the control of the hypothalamus
How are vasopressin (ADH) and oxytocin transported and stored?
Synthesized in hypothalamus, then stored in posterior pituitary
What senses plasma osmolarity to stimulate the release of certain hormones from the posterior pituitary?
Osmoreceptors in the hypothalamus
What condition is often associated with the hypersecretion of ACTH by anterior pituitary adenomas?
Cushing syndrome
What is acromegaly?
Excessive growth hormone secretion in adults
What is the most common cause of acromegaly?
Adenoma in anterior pituitary gland
How can acromegaly be diagnosed?
Elevated serum IGF-1 levels
What test can be performed to assess acromegaly?
Oral glucose tolerance test
What surgery is the main treatment for acromegaly?
Transsphenoidal excision of pituitary adenoma
What is the alternative treatment option for acromegaly if surgery is not feasible?
LA somatostatin analogue
What are the anesthesia implications for patients with acromegaly?
Obstructed airway, need for smaller ETT
How does acromegaly affect the placement of a face mask during anesthesia?
Interferes due to distorted facial anatomy
Why may visualizing the vocal cords be challenging in acromegaly patients during direct laryngoscopy?
Enlarged tongue and epiglottis
What does diabetes insipidus (DI) reflect?
Absence of vasopressin (ADH)
How is neurogenic DI differentiated from nephrogenic DI?
Response to desmopressin
What are the symptoms of diabetes insipidus?
Polydipsia and high output of poorly concentrated urine
What is the initial treatment for diabetes insipidus?
IV e-lytes to offset polyuria
How is neurogenic DI treated?
DDAVP
How is nephrogenic DI treated?
Low-salt, low-protein diet, diuretics, NSAIDs
What should be monitored during anesthesia for a patient with DI?
Urine output & serum electrolyte concentrations
What diverse pathologies can cause Syndrome of Inappropriate ADH (SIADH)?
Intracranial tumors, hypothyroidism, porphyria, lung carcinoma
What is a common occurrence in most patients following major surgeries in relation to ADH levels?
Elevated ADH levels
What is highly suggestive of SIADH?
Inappropriately increased urinary sodium and osmolarity with hyponatremia and decreased serum osmolarity
What can abrupt decreases in serum sodium concentration lead to?
Cerebral edema and seizures
What are the treatments for SIADH?
Fluid restriction, salt tablets, loop diuretics & vasopressin antagonists
How should hyponatremia be treated at less than 8 mEq/L within 24 hours?
With hypertonic saline
