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Questions and Answers
What is the primary function of human growth hormone (GH) produced by the anterior pituitary?
Which hormone is responsible for stimulating ovulation in females?
What condition results from excess secretion of ACTH?
Which part of the pituitary gland secretes oxytocin?
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What causes the inhibition of growth hormone release?
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Which of the following is not a function of the anterior pituitary hormones?
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What physiological role does arginine vasopressin (AVP) play?
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Which hormone increases the rate of protein synthesis and mobilizes fatty acids?
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What is a primary cause of Diabetes insipidus?
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Which hormone is primarily responsible for milk secretion during lactation?
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Which condition is characterized by soft tissue overgrowth affecting the epiglottis and vocal cords?
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What is the primary hormone deficiency in neurogenic diabetes insipidus?
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In patients with acromegaly, what airway management technique should be considered if intubation is predicted to be difficult?
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What is the primary treatment option for patients with acromegaly when transsphenoidal resection is not feasible?
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What physiological change does aldosterone primarily induce?
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Which of the following is NOT a common consequence of SIADH?
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What is a significant risk associated with the management of patients with acromegaly regarding arterial catheterization?
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What is the appropriate treatment approach for nephrogenic diabetes insipidus?
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What dimension of the adrenal cortex primarily secretes glucocorticoids?
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What is the maximum safe correction of serum sodium levels in SIADH treatment over 24 hours?
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What is the primary treatment focus for managing hypertension associated with pheochromocytoma?
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Which of the following is a characteristic symptom of pheochromocytoma?
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In preparing a patient for pheochromocytoma surgery, phenoxybenzamine should be discontinued how long before the procedure?
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What is a common cause of hypertensive episodes in patients with pheochromocytoma?
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What is the mechanism of action of metyrosine in pheochromocytoma management?
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Which of the following is NOT a method to prevent catecholamine release during intraoperative management of pheochromocytoma?
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Which medication should be avoided if a patient is already on an alpha blocker during pheochromocytoma treatment?
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In what location is a majority of pheochromocytoma tumors found?
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What is the major concern for a patient who has undergone ligation of pheochromocytoma in terms of blood pressure?
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Which medication is recommended to manage hypertension during pneumoperitoneum?
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In Cushing's syndrome, which symptom is commonly observed in addition to hypertension?
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What is the recommended treatment approach for Conn's syndrome?
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Which pharmacological agents should be avoided due to their ability to cause histamine release in anesthetic management?
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What is the typical post-operative blood pressure management strategy for patients who have had pheochromocytoma surgery?
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What is the primary cause of secondary adrenal insufficiency?
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Which condition may require a 'stress dose' of steroids during surgery?
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Which vascular access method is sometimes necessary for guiding fluid therapy in patients undergoing surgery for pheochromocytoma?
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Which adverse effect is associated with the use of Phentolamine in hypertension treatment?
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In the management of Addison's disease, what lab value indicates primary adrenal insufficiency?
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Which anesthetic drug can decrease both catecholamine release and receptor sensitivity during surgical procedures?
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Study Notes
Pituitary Gland
- Small, bilobed gland located beneath the hypothalamus, approximately the size of a pea
- Divided into anterior and posterior segments
- Anterior pituitary: adenohypophysis, originates from upper GI cells during development
- Posterior pituitary: neurohypophysis, derived from neural tissue
- Secretes hormones that regulate a wide range of bodily functions, including homeostasis, growth, reproduction, lactation, and thyroid hormone release
Anterior Pituitary Hormones
-
Human growth hormone (somatotropin):
- Secreted by somatotropin cells
- Accelerates body growth and has insulin antagonistic effects
-
Prolactin:
- Secreted by lactotropes
- Stimulates milk secretion and maternal behavior
- Inhibits ovulation
-
Luteinizing hormone:
- Secreted by gonadotropes
- Stimulates ovulation in females
- Stimulates testosterone secretion in males
-
Follicle-stimulating hormone:
- Secreted by gonadotropes
- Stimulates ovarian follicle growth in females
- Stimulates spermatogenesis in males
-
Adrenocorticotrophic hormone:
- Secreted by corticotropes
- Stimulates adrenal cortex secretion and growth
- Promotes steroid production
-
Thyroid-stimulating hormone:
- Secreted by thyrotropes
- Stimulates thyroid secretion and growth
-
β-Lipotropin:
- Secreted by corticotropes
- Precursor of endorphins
Posterior Pituitary Hormones
-
Arginine vasopressin:
- Synthesized in the supraoptic nuclei
- Promotes water retention and regulates plasma osmolarity
-
Oxytocin:
- Synthesized in the paraventricular nuclei
- Causes milk ejection and uterine contraction
Anterior Pituitary Disorders
-
Acromegaly:
- Excessive growth hormone production, often due to an adenoma in the anterior pituitary
- Symptoms:
- Skeletal overgrowth, including prognathism
- Soft tissue overgrowth, including lips, tongue, epiglottis, and vocal cords
- Connective tissue overgrowth, potentially leading to recurrent laryngeal nerve paralysis
- Visceromegaly
- Glucose intolerance and diabetes mellitus
- Osteoarthritis and osteoporosis
- Hyperhidrosis
- Skeletal muscle weakness
- Peripheral neuropathies due to nerve entrapment, especially carpal tunnel syndrome and ulnar nerve involvement
- Increased incidence of hypertension and ischemic heart disease
- Treatment:
- Preferred initial therapy is transsphenoidal resection of the pituitary
- If adenoma extends beyond the sella turcica, long-acting somatostatin may be used
Anesthetic Management of Acromegaly
- Airway management is a primary concern due to facial distortion, tongue and epiglottis enlargement, and a potentially narrower glottic opening
- Awake fiberoptic intubation should be considered if difficult intubation is anticipated
- Radial artery catheterization should be used cautiously due to potential ulnar artery compression
- Glucose monitoring is essential
Posterior Pituitary Disorders
-
Diabetes Insipidus:
- Deficiency of ADH due to:
- Destruction of the posterior pituitary (neurogenic DI)
- Failure of renal tubules to respond to ADH (nephrogenic DI)
- Symptoms: polydipsia and high output of dilute urine despite increased osmolality
- Treatment:
- Oral intake initially, followed by IV infusions of electrolytes and fluids
- Neurogenic DI: desmopressin
- Nephrogenic DI: low-sodium, low-protein diet, diuretics, and NSAIDs
- Deficiency of ADH due to:
-
SIADH:
- Excessive ADH secretion due to:
- Tumors
- Hypothyroidism
- Porphyria
- Lung carcinoma
- Postoperative complications
- Symptoms: increased urinary sodium and osmolality, and decreased serum sodium and osmolality
- Treatment:
- Fluid restriction
- High solute intake
- Salt tablets
- Diuretics
- Vasopressin receptor antagonists
- IV hypertonic saline in resistant cases (with careful monitoring due to risk of central pontine myelinolysis)
- Excessive ADH secretion due to:
Adrenal Glands
- Cortical hormones are classified into three major groups:
- Mineralocorticoids
- Glucocorticoids
- Androgens
- Cholesterol is the precursor for all corticosteroids
- The adrenal cortex is divided into three zones:
- Zona glomerulosa: secretes mineralocorticoids
- Zona fasciculata: secretes glucocorticoids
- Zona reticularis: secretes androgens and estrogens
Zona Glomerulosa: Mineralocorticoids
- Primarily secretes aldosterone (95%)
- Increases extracellular fluid volume by increasing sodium and water reabsorption
- Decreases potassium concentration
- Secretion is stimulated by increased potassium concentration and the renin-angiotensin-aldosterone system
- Mineralocorticoid activity is not regulated by ACTH
Zona Fasciculata: Glucocorticoids
- Primarily secretes cortisol (95%)
- Functions:
- Developmental changes, especially during pregnancy
- Gluconeogenesis (amplified by 10 times), potentially leading to adrenal diabetes
- Protein catabolism, breaking down protein stores in all tissues except the liver
- Fatty acid metabolism, potentially leading to "buffalo hump" fat accumulation
- Anti-inflammatory effects, stabilizing liposomal membranes and decreasing white blood cell migration
- Perioperative stress increases ACTH and cortisol release, peaking during NMBA reversal and extubation
- Exogenous steroid users are unable to produce their own cortisol during stress and require "stress doses" (100-200mg hydrocortisone)
Adrenal Gland Disorders
-
Pheochromocytoma:
- Catecholamine-secreting tumor, often located in the adrenal medulla, but may also be found in other locations like the organ of Zuckerkandl, neck, and thorax
- Can cause malignant hypertension, cerebrovascular accidents, and myocardial infarctions
- Typically associated with hypertension and symptoms like sweating, headache, abdominal pain, nausea, vomiting, diarrhea, pallor, tremor, anxiety, and panic
- Preoperative management:
- Alpha-blockade (phenoxybenzamine, prazosin, or doxazosin) to lower blood pressure, increase intravascular volume, prevent hypertensive episodes, and decrease myocardial dysfunction
- Beta-blockade (atenolol, labetalol, metoprolol, esmolol) in selected patients with tachycardia, but only after alpha-blockade
- Metyrosine to inhibit catecholamine production
- Intraoperative management:
- Proper preparation with alpha and beta blockade, correction of hypovolemia, and avoidance of catecholamine-releasing stimuli
- Intravenous fluids, vasoactive medications, and vigilant hemodynamic monitoring
- Hypotension is common after tumor ligation due to dependence on extra catecholamines and long-acting alpha blockers
- Hypertension is common during pneumoperitoneum, but laparoscopy is still preferred to laparotomy
- Arrhythmias are typically ventricular, and are managed with beta blockers or lidocaine
- Postoperative management:
- Hypoglycemia and persistent hypertension are possible
- Hypotension is a significant risk, requiring careful fluid management and possibly vasopressors
- Steroid supplementation may be necessary
-
Cushing Syndrome:
- Excessive cortisol production due to ACTH dependence (excessive ACTH stimulating the adrenal cortex) or ACTH independence (abnormal adrenocortical tissue)
- Symptoms: central weight gain, hypertension, glucose intolerance, and skeletal muscle weakness
- Treatment: transsphenoidal microadenomectomy or resection of the anterior pituitary
- Anesthetic management is not significantly influenced by hypercortisolism
-
Conn Syndrome:
- Excess aldosterone secretion from an adenoma, not under physiologic control
- Symptoms: hypertension, headache, polyuria, nocturia, and muscle cramps or weakness
- Treatment: potassium supplementation, aldosterone antagonists, and surgical excision of the tumor
- Anesthetic management:
- Preoperative correction of potassium and treatment of hypertension
- Avoidance of hyperventilation
- Pulmonary artery catheterization or transesophageal echocardiogram
- Exogenous cortisol administration
-
Addison's Disease:
- Primary adrenal insufficiency: adrenal glands fail to produce glucocorticoids, mineralocorticoids, and androgen hormones
- Secondary adrenal insufficiency: failure to produce CRH or ACTH due to hypothalamic-pituitary disease, leading to a decrease in glucocorticoid production specifically
- Treatment: exogenous steroids
- Anesthetic management:
- Treatment of hemodynamic instability
- "Stress dose" of hydrocortisone (100mg every 6 hours)
- Correction of volume deficits
- No specific technique or medication is favored
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