Pheochromocytoma and Related Disorders Quiz
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Questions and Answers

What is the primary treatment for hypertension in pheochromocytoma patients preoperatively?

  • Beta blockade
  • Calcium channel blocker
  • Alpha blockade (correct)
  • Sodium nitroprusside

    • Which of the following symptoms is least commonly associated with pheochromocytoma?

  • Hypertension
  • Sweating
  • Hypoglycemia (correct)
  • Anxiety and panic

    • What is the mechanism of action of metyrosine in treating pheochromocytoma?

  • Inhibits catecholamine production (correct)
  • Blocks adrenergic receptors
  • Promotes catecholamine release
  • Inhibits aldosterone secretion

    • Which medication should NOT be administered prior to alpha blockade during preoperative management of pheochromocytoma?

    <p>Labetalol</p> Signup and view all the answers

    Following surgery for pheochromocytoma, what is a critically important postoperative concern?

    <p>Hypotension</p> Signup and view all the answers

    What characterizes ACTH-dependent Cushing Syndrome?

    <p>High levels of plasma ACTH</p> Signup and view all the answers

    What test is used to diagnose Conn Syndrome?

    <p>Spontaneous hypokalemia with systemic hypertension</p> Signup and view all the answers

    Which of the following is a symptom of Cushing Syndrome?

    <p>Skin thinning</p> Signup and view all the answers

    What is the typical treatment for Addison's Disease during stress conditions?

    <p>Exogenous steroids</p> Signup and view all the answers

    What is the potential effect of hyperventilation in patients with hypokalemia?

    <p>Decreases potassium levels</p> Signup and view all the answers

    What is a common consequence of ligation of a pheochromocytoma?

    <p>Severe hypotension</p> Signup and view all the answers

    In which demographic does familial pheochromocytoma typically manifest?

    <p>Both adults and children</p> Signup and view all the answers

    Which of the following drugs is effective in treating refractory hypertension after pheochromocytoma resection?

    <p>Sodium nitroprusside</p> Signup and view all the answers

    What additional management may be required postoperatively for Addison's disease patients?

    <p>Stress dose of hydrocortisone</p> Signup and view all the answers

    What is the primary hormone secreted by the thyroid gland that plays a critical role in metabolism?

    <p>Thyroxine (T4)</p> Signup and view all the answers

    Which condition is characterized by low Thyroid-Stimulating Hormone (TSH) levels alongside elevated T4 and T3?

    <p>Graves disease</p> Signup and view all the answers

    Which medication can be used as a first-line treatment for hyperthyroidism?

    <p>Methimazole</p> Signup and view all the answers

    What is a potential risk associated with general anesthesia in patients with hypothyroidism?

    <p>Airway compromise</p> Signup and view all the answers

    In what situation might a patient experiencing thyroid storm present similar to malignant hyperthermia during surgery?

    <p>Hyperpyrexia and tachycardia</p> Signup and view all the answers

    What distinguishes primary hyperparathyroidism from secondary hyperparathyroidism?

    <p>Increased secretion of Parathyroid hormone (PTH)</p> Signup and view all the answers

    Which factor is most commonly associated with the development of myxedema coma?

    <p>Chronic untreated hypothyroidism</p> Signup and view all the answers

    What is the primary aim of treatment for hypoparathyroidism?

    <p>Elevate plasma calcium concentrations</p> Signup and view all the answers

    What is a common symptom of primary hyperparathyroidism related to the nervous system?

    <p>Somnolence</p> Signup and view all the answers

    What complication can arise from a parathyroidectomy?

    <p>Hypoparathyroidism</p> Signup and view all the answers

    Which pituitary hormone is responsible for stimulating lactation and maternal behavior?

    <p>Prolactin</p> Signup and view all the answers

    Which condition is most often caused by an adenoma in the anterior pituitary?

    <p>Acromegaly</p> Signup and view all the answers

    What is the effect of glucocorticoids in the treatment of thyroid storm?

    <p>Decrease hormone release</p> Signup and view all the answers

    In patients with chronic hypoparathyroidism, which of the following is a significant cardiac manifestation?

    <p>Prolonged QT interval</p> Signup and view all the answers

    What is the primary hormone secreted by the thyroid gland that significantly influences metabolism?

    <p>Thyroxine (T4)</p> Signup and view all the answers

    An elevated TSH level is characteristic of hyperthyroidism.

    <p>False</p> Signup and view all the answers

    What is the most common cause of hypothyroidism in the US?

    <p>Thyroid removal</p> Signup and view all the answers

    The condition characterized by an underactive thyroid gland is known as _____ .

    <p>Hypothyroidism</p> Signup and view all the answers

    Match the following conditions with their descriptions:

    <p>Graves Disease = Autoimmune hyperthyroidism Hashimoto Thyroiditis = Autoimmune hypothyroidism Acromegaly = Excess growth hormone secretion Cushing Syndrome = Excess cortisol production</p> Signup and view all the answers

    Which of the following treatments is used in patients with hyperthyroidism?

    <p>Both A and C</p> Signup and view all the answers

    Thyroid storm may present with normal levels of thyroid hormones.

    <p>True</p> Signup and view all the answers

    Which vitamin is important for calcium absorption related to parathyroid function?

    <p>Vitamin D</p> Signup and view all the answers

    The thyroid gland is located in the neck and surrounds the _____ .

    <p>trachea</p> Signup and view all the answers

    What is a significant postoperative concern after a parathyroidectomy?

    <p>Hypocalcemia</p> Signup and view all the answers

    Secondary hyperparathyroidism is characterized by hypercalcemia.

    <p>False</p> Signup and view all the answers

    Name a treatment method for myxedema coma.

    <p>L-thyroxine or L-triiodothyronine</p> Signup and view all the answers

    An injury to the recurrent laryngeal nerve can lead to _____ voice.

    <p>hoarse</p> Signup and view all the answers

    Match the following pituitary hormones with their primary actions:

    <p>Prolactin = Stimulate lactation ADH = Promote water retention ACTH = Stimulate cortisol production LH = Stimulate ovulation</p> Signup and view all the answers

    What percentage of pheochromocytomas are usually familial?

    <p>10%</p> Signup and view all the answers

    Pheochromocytomas predominantly produce cortisol, leading to Cushing syndrome.

    <p>False</p> Signup and view all the answers

    What is the most frequently used alpha blocker for pheochromocytoma?

    <p>Phenoxybenzamine</p> Signup and view all the answers

    Patients with adrenal insufficiency will require a ______ during times of stress.

    <p>stress dose of hydrocortisone</p> Signup and view all the answers

    Match the adrenal disorders to their characteristics:

    <p>Cushing Syndrome = Excess cortisol production Conn Syndrome = Excess aldosterone secretion Addison's Disease = Primary adrenal insufficiency Pheochromocytoma = Catecholamine-secreting tumor</p> Signup and view all the answers

    Which symptom is NOT commonly associated with pheochromocytoma?

    <p>Weight loss</p> Signup and view all the answers

    Patients with Addison's disease do not produce any glucocorticoids.

    <p>True</p> Signup and view all the answers

    What is the main treatment for Conn Syndrome?

    <p>Aldosterone antagonist like spironolactone</p> Signup and view all the answers

    Metyrosine inhibits the enzyme ______, reducing catecholamine production.

    <p>tyrosine hydroxylase</p> Signup and view all the answers

    Postoperative hypertension is common in what percentage of pheochromocytoma patients?

    <p>50%</p> Signup and view all the answers

    Hypotension after ligation of pheochromocytoma is due to decreased catecholamine release.

    <p>True</p> Signup and view all the answers

    How is Conn Syndrome diagnosed?

    <p>Spontaneous hypokalemia with systemic hypertension</p> Signup and view all the answers

    Cushing syndrome is characterized by high plasma levels of ______.

    <p>ACTH or cortisol</p> Signup and view all the answers

    What common surgery is performed to treat Cushing syndrome?

    <p>Transsphenoidal microadenomectomy</p> Signup and view all the answers

    Study Notes

    Thyroid Gland

    • Located in the neck, surrounding the trachea caudal to the larynx, connected by a bridge of tissue called the thyroid isthmus.
    • Responsible for maintaining optimal metabolism for normal tissue function.
    • Secretes thyroxine (T4) and triiodothyronine (T3).
    • T4 is a prohormone synthesized from tyrosine and makes up 80% of thyroid hormone production.
    • T3 is 5X more active than T4 and is produced from tyrosine metabolism or from conversion from T4.
    • Thyroid hormone actions include increased O2 consumption in almost all tissues.
    • Cardiovascular signs are often the earliest signs of thyroid dysfunction and alter MAC requirements for volatile anesthesia.

    Hyperthyroidism

    • Caused by Graves disease, toxic multinodular goiter, or toxic adenoma.
    • Graves disease is the leading cause, affecting 0.4% of Americans.
    • Graves disease is a systemic autoimmune disease characterized by thyroid stimulating antibodies binding to TSH receptors in the thyroid, stimulating growth, vascularity, and hypersecretion of T4 and T3.
    • Toxic multinodular goiter arises from long-term goiter and may cause dysphagia with tracheal compression.
    • Toxic adenoma is a neoplasm requiring a CT scan for differentiation.

    Treatment for Hyperthyroidism

    • First line therapy is antithyroid drugs such as methimazole or propylthiouracil.
    • Iodide inhibits the release of hormones from the thyroid gland, primarily used in preparation for surgery, managing thyroid storm, or treating severe thyrocardiac cases.
    • Beta blockers can decrease cardiac symptoms.
    • Ablative therapy with radioactive 1311 (radioiodine) or surgery is used for those with failed Graves treatment, a goiter, or toxic adenoma.
    • Total or subtotal thyroidectomy can lead to tracheal compression, uni- or bilateral RLN damage, damage to the motor branch of the SLN, or damage to the parathyroids.

    Thyroid Storm

    • A life-threatening exacerbation of hyperthyroidism often precipitated by trauma, infection, medical illness, or surgery, that can present similarly to malignant hyperthermia.
    • Characterized by hyperpyrexia, tachycardia, and hypermetabolism, and may have normal thyroid levels, with a 20% mortality rate.
    • Treatment involves rapid alleviation of thyrotoxicosis in conjunction with supportive care.
    • Glucocorticoids slow the conversion of T4 to T3, beta blockers decrease SNS flow, and antithyroid drugs block hormone synthesis.

    Hypothyroidism

    • Affects 0.5% - 0.8% of adults, with 95% of cases due to decreased production of thyroid hormones despite adequate or increased TSH.
    • The most common cause in the US is thyroid removal, second is idiopathic, likely autoimmune.
    • Hashimoto thyroiditis is an autoimmune disease with goiterous enlargement and hypothyroidism.
    • Symptoms are slow, insidious, and progressive, with subclinical hypothyroidism being present in 20% of geriatric females.

    Treatment of Hypothyroidism

    • Levothyroxine sodium replaces T4 hormone, resulting in sodium and water diuresis and reduction in TSH level.
    • Levothyroxine can lead to angina, complicating treatment.
    • Angiography is recommended for patients with hypothyroidism and angina.

    Anesthetic Management of Hypothyroidism

    • Patients with hypothyroidism are at risk for:
      • Airway compromise
      • Aspiration
      • Hypodynamic cardiac system
      • Hypoxia
      • Hypothermia
      • Electrolyte imbalances
    • Patients with hypothyroidism are extremely sensitive to opioids and other sedatives.
    • Steroid coverage (stress dose) will be needed due to likely adrenal suppression.

    Hypothyroidism: Myxedema Coma

    • A rare, severe form of hypothyroidism with a mortality rate > 50%, requiring a medical emergency.
    • Symptoms include delirium, hypoventilation, and hypothermia.

    Goiter and Thyroid Tumors

    • Swelling of the thyroid gland that can be caused by poor intake of iodine, ingestion of dietary or pharmacologic goitrogen, or defects in the biotransformation pathway.
    • Most often presents in a euthyroid state, but surgery is indicated if medical therapy is ineffective.
    • Can lead to caval obstruction, airway obstruction, or cardiac compression in extremes of growth.
    • Airway/ventilation changes can occur with position/postural changes.
    • Preop history of dyspnea in upright or supine position is predictive of airway obstruction.

    Anesthetic Management of Goiter and Thyroid Tumors

    • AFOI with an armored tube is recommended to maintain airway safety, especially in patients with goiter.
    • Ensure bilateral cord movement with airway exam prior to extubation.
    • Keep CPB equipment on standby.

    Thyroid Surgery Complications

    • Morbidity near 13%
    • The RLN provides motor innervation to all laryngeal muscles except the cricothyroid and sensory innervation to below the cords.
    • The right RLN loops under the innominate artery, while the left RLN loops under the aortic arch.
    • Unilateral RLN injury results in hoarseness, while bilateral RLN injury may cause a loss of vocal cord function and require a tracheostomy.
    • The SLN injury results in a weakening of the voice.
    • Hypoparathyroidism can be caused by damage to the blood supply, leading to hypocalcemia within 24-48 hours of surgery.
    • Tracheal compression due to a hematoma may require evacuation of the hematoma, re-entry, or tracheostomy.

    Parathyroid Glands

    • Four glands that secrete PTH which regulates calcium concentration.
    • Secretion of PTH is inversely related to plasma calcium concentration.
    • Functions include:
      • Mobilization of bone calcium
      • Enhancing conversion of vitamin D to active form
      • Increasing renal tubular absorption of calcium
      • Inhibiting renal absorption of phosphate.

    Primary Hyperparathyroidism

    • Results from excessive secretion of PTH due to:
      • Benign PT adenoma
      • Carcinoma of PT
      • Hyperplasia of the PT
    • Diagnosed with hypercalcemia (serum > 5.5mEq/L OR ionized Ca > 2.5 mEq/L).
    • The most common cause of hypercalcemia in the general population.
    • Cancer is the most common cause in hospitalized patients.
    • Treatment involves removal of the PT glands, with normalization of calcium expected 3-4 days postoperatively.

    Parathyroidectomy Postoperative Concerns

    • Postoperative tetany due to hypocalcemia, exacerbated by hypomagnesemia.
    • Transient hyperchloremic metabolic acidosis can occur due to deteriorating renal function.

    Anesthetic Management of Primary Hyperparathyroidism

    • No evidence that any medications or techniques are necessary.
    • Hydration and urine output are crucial.
    • Careful positioning and padding is needed due to weakened bones.
    • Coexisting muscular weakness may suggest a decreased requirement for muscle relaxation.
    • Monitor for EKG changes.

    Secondary Hyperparathyroidism

    • Compensation for a pathology that leads to hypocalcemia.
    • Rarely leads to hypercalcemia.
    • Treatment is directed towards normalizing serum phosphate in patients with renal disease by administering a phosphate binder orally.

    Hypoparathyroidism

    • Characterized by absent, deficient, or resistant PTH.
    • Most often iatrogenic, occurring with inadvertent removal of the parathyroid during thyroidectomy.
    • Pseudohypoparathyroidism is a congenital disorder with PTH release but no kidney response to the hormone, characterized by mental retardation, calcified basal ganglia, obesity, short fingers and toes.
    • Diagnosed by hypocalcemia (serum < 4.5mEq/L OR ionized < 2mEq/L) with low or inappropriately normal PTH hormone and hyperphosphatemia.
    • Treatment involves calcium gluconate or calcium chloride, correction of respiratory or metabolic alkalosis, and calcium/vitamin D.

    Anesthetic Management of Hypoparathyroidism

    • Focuses on preventing further decreases in calcium and treating adverse effects of hypocalcemia.
    • Monitor for cardiac symptoms.
    • Hyperventilation and bicarbonate administration can decrease calcium levels.

    Pituitary Gland: The Master Gland

    • A bilobed body located beneath the hypothalamus, approximately the size of a pea.
    • Divided into anterior (adenohypophysis) and posterior (neurohypophysis) segments.
    • Releases hormones that control body processes including regulation of homeostasis, growth, reproduction, lactation, and thyroid hormone regulation.

    Anterior Pituitary Disorders

    • Acromegaly: too much growth hormone.
      • Most often caused by an adenoma in the anterior pituitary.
    • Symptoms include skeletal overgrowth, soft tissue overgrowth, connective tissue overgrowth, visceromegaly, glucose intolerance/DM, osteoarthritis, osteoporosis, hyperhidrosis, skeletal muscle weakness, peripheral neuropathies, and increased incidence of hypertension and ischemic heart disease.

    Treatment for Acromegaly

    • Preferred therapy is transsphenoidal resection of the pituitary.
    • Long-acting somatostatin is used if adenoma is not resectable.

    Anesthetic Management of Acromegaly

    • Airway is a primary concern:
      • Facial distortion, tongue and epiglottis enlargement, turbinate enlargement, and narrow glottic opening can make ventilation challenging.
      • Ulnar artery compression may make radial artery catheterization detrimental.
    • Glucose monitoring is also a priority.

    Posterior Pituitary Disorders

    Diabetes Insipidus

    • Not enough ADH.
    • Caused by destruction of the posterior pituitary (neurogenic DI) or failure of the renal tubules to respond to ADH (nephrogenic DI).
    • Symptoms include polydipsia and high output of dilute urine despite increased osmolality.
    • Transient type occurs after pituitary surgery secondary to trauma to the posterior pituitary.
    • Treatment includes oral intake, IV infusions of electrolytes and fluids, desmopressin (neurogenic DI), or a low-sodium, low-protein diet, diuretics, and NSAIDs (nephrogenic DI).

    SIADH

    • Too much ADH.
    • Common causes include tumors, hypothyroidism, porphyria, and lung carcinoma.
    • Inappropriate secretion of ADH occurs during/following major surgeries.
    • Symptoms include decreased serum sodium and osmolality, and increased urinary sodium and osmolality.
    • Treatment includes fluid restriction, high solute intake, salt tablets, diuretics, vasopressin receptor antagonists, or IV hypertonic saline.

    Adrenal Glands

    • Adrenal cortex secretes mineralocorticoids, glucocorticoids, and androgens.
    • Precursor of all corticosteroids is cholesterol.
    • Divided into three zones: zona glomerulosa, zona fasciculata, and zona reticularis.

    Zona Glomerulosa: Mineralocorticoids

    • Primarily aldosterone.
    • Increases ECF volume via the increase reabsorption of sodium and thus water, and decreases potassium concentration.
    • Secretion is stimulated by increased potassium concentration and function of the RAAS.
    • Mineralocorticoid activity is not regulated by ACTH.

    Zona Fasciculata: Glucocorticoids

    • Primarily cortisol.
    • Functions include:
      • Developmental changes
      • Gluconeogenesis
      • Protein catabolism
      • Fatty acid metabolism
      • Anti-inflammatory effects
    • Perioperative stress will increase ACTH and cortisol release.
    • Deep extubation or avoiding the ETT can decrease this response.
    • Must accommodate patients taking exogenous steroids.

    Adrenal Gland Disorders

    • Pheochromocytoma is a catecholamine-secreting tumor that can lead to malignant hypertension, stroke, and myocardial infarction.
    • 80% of pheochromocytomas are found in the adrenal medulla, with the remaining 20% found in the organ of Zuckerkandl, neck, or thorax.
    • They account for 0.1% of hypertension in adults but have a high mortality risk.
    • Diagnosis is made by urine testing to measure plasma-free metanephrine and metanephrine levels.
    • Symptoms of pheochromocytoma include hypertension, sweating, headache, anxiety, and panic.
    • Less common symptoms include abdominal pain, nausea, vomiting, diarrhea, pallor, hallucinations, agitation/apprehension, tremor.
    • Preoperative management involves alpha blockade, beta blockade, and metyrosine.
    • Alpha blockers are preferred for lowering blood pressure, increasing intravascular volume, preventing hypertensive episodes, and decreasing myocardial dysfunction.
    • Beta blockers are used in select patients who have tachycardia.
    • Metyrosine inhibits tyrosine hydroxylase from producing catecholamines by inducing calcium channel blockade.
    • Intraoperative management requires alpha blockade with or without beta blockade, correction of hypovolemia, and avoiding drugs or maneuvers that cause catecholamine release.
    • Avoid histamine-releasing drugs like morphine, atracurium, and mivacurium.
    • Intraoperative BP control is achieved with short-acting agents, and an arterial line and central venous pressure monitoring are recommended.
    • Hypotension is common after ligation of the pheochromocytoma due to dependence on extra catecholamines produced by the tumor and long-acting alpha blockers.
    • Hypertension is common during pneumoperitoneum, even with proper preparation.
    • Sodium nitroprusside is the agent of choice for hypertension.
    • Refractory hypertension can be managed with a combination of sodium nitroprusside, esmolol, diltiazem, and phentolamine.
    • Arrhythmias are typically ventricular, and beta blockers and/or lidocaine are used for treatment.
    • Postoperative management includes monitoring for hypoglycemia, hypertension, and hypotension.
    • Hypoglycemia is possible due to the lack of cortisol production.
    • Hypertension is common for several days after surgery, with 20-30% of patients permanently hypertensive.
    • Hypotension is the most frequent cause of death after surgery and requires large volumes of fluid and sometimes vasopressors.
    • Steroid supplementation may be required.

    Cushing Syndrome

    • Characterized by excessive cortisol production.
    • ACTH-dependent Cushing syndrome is caused by high plasma ACTH levels stimulating the adrenal cortex.
    • ACTH-independent Cushing syndrome is caused by excessive production of cortisol by abnormal adrenocortical tissue.
    • Symptoms include central weight gain, hypertension, glucose intolerance, and skeletal muscle weakness.
    • Diagnosis is made by measuring cortisol concentration in a 24-hour urine sample.
    • Treatment includes transsphenoidal microadenomectomy or resection of the anterior pituitary.

    Conn Syndrome

    • Characterized by excessive aldosterone secretion from an adenoma.
    • Associated with pheochromocytoma, hyperparathyroidism, and acromegaly.
    • Symptoms include hypertension, headache, polyuria, nocturia, muscle cramps or weakness.
    • Diagnosis is made by spontaneous hypokalemia with systemic hypertension.
    • Treatment includes potassium supplementation, aldosterone antagonists like spironolactone, potassium-sparing diuretics like triamterene, and surgical excision of the tumor.

    Anesthetic Management for Conn Syndrome:

    • Preoperative correction of potassium and treatment of hypertension are essential.
    • Avoid hyperventilation, as it can further decrease potassium.
    • Pulmonary artery catheter or transesophageal echocardiogram may be necessary to measure filling pressures.
    • Fluid replacement is key.
    • Exogenous cortisol administration may be required.

    Addison's Disease

    • Primary adrenal insufficiency is caused by the adrenal glands' failure to produce glucocorticoids, mineralocorticoids, or androgen hormones.
    • 90% of cases are autoimmune.
    • Secondary adrenal insufficiency is caused by a failure to produce CRH or ACTH due to hypothalamic-pituitary disease.
    • Diagnosis is made by baseline plasma cortisol level <20 mcg/dL and cortisol <20 mcg/dL after ACTH stimulation.
    • Treatment involves exogenous steroids.
    • Patients on chronic steroid therapy are unable to produce their own cortisol during times of stress and require a "stress dose" of hydrocortisone.
    • Steroid therapy decreases cortisol production for five days after discontinuation.

    Anesthetic Management for Addison's Disease:

    • Treat hemodynamic instability if present.
    • Administer hydrocortisone 100 mg every 6 hours.
    • Correct volume deficits, which can be substantial.

    Thyroid Gland

    • Located in the neck, surrounding the trachea.
    • Secretes thyroxine (T4) and triiodothyronine (T3).
    • T4 is a prohormone, T3 is 5X more active.
    • Both hormones are synthesized from tyrosine.
    • Actions of thyroid hormones increase oxygen consumption in most tissues.
    • CV signs are often the earliest signs of dysfunction.
    • Alters MAC requirements for volatile anesthetics.
      • This was more relevant with halothane, as it is metabolized at 20%.
      • Sevoflurane is metabolized at only 2%, so MAC requirements likely won't change much.

    Hyperthyroidism

    • Three major causes:
      • Graves disease: most common cause, an autoimmune disease.
        • Characterized by low TSH, elevated T4 and T3, and presence of thyroid-stimulating antibodies.
      • Toxic multinodular goiter: can lead to dysphagia due to increased size (tracheal compression).
      • Toxic adenoma: a neoplasm.
    Signs & Symptoms of Hyperthyroidism
    General
    HEENT
    CV
    Neuro
    GI
    Psych
    Skin

    Thyroid Storm

    • A life-threatening exacerbation of hyperthyroidism often precipitated by trauma, infection, medical illness, or surgery.
    • Presents intraoperatively like MH: hyperpyrexia, tachycardia, and hypermetabolism.
    • Can have normal thyroid levels.
    • Occurs most often in the postop period.
    • Mortality rate is 20%.
    Thyroid Storm Treatment Effect
    Glucose IV fluid Treat dehydration
    Beta blockers Decrease SNS flow
    Glucocorticoids Decrease hormone release and slow T4 to T3 conversion
    Antithyroid Drug Block hormone synthesis

    Hypothyroidism

    • AKA Myxedema, affects 0.5% - 0.8% of adults.
    • 95% of cases are due to decreased production of thyroid hormones despite adequate or increased TSH.
    • Most common cause in the US is thyroid removal, second most common is idiopathic.
    • S&S: slow, insidious, progressive course.

    Treatment for Hypothyroidism

    • Levothyroxine sodium: replaces T4 hormone.
      • Evidence of efficacy: sodium and water diuresis and reduction of TSH level.
      • Improves cardiac function in patients with cardiomyopathy.
    Signs & Symptoms of Hypothyroidism
    General
    HEENT
    CV
    Neuro
    GI
    Psych
    Skin

    Hypothyroidism: Myxedema Coma

    • Rare, severe form of hypothyroidism.
    • Symptoms: delirium, hypoventilation, hypothermia (80% of patients).
    • Mortality rate > 50%.
    • Medical emergency.
    • TX: L-thyroxine or L-triiodothyronine with hydration and temp correction with mechanical ventilation if needed.

    Goiter and Thyroid Tumors

    • Swelling of the thyroid gland typically caused by poor intake of iodine, ingestion of goitrogen or a defect in biotransformation pathway.
    • In most cases, a euthyroid state is present.
    • Can lead to caval obstruction, airway obstruction, cardiac compression in extremes of growth.
    • Airway/ventilation changes can occur with position/postural changes.
    • CT scan is necessary to assess extent of the tumor.

    Anesthetic Management of Goiter and Thyroid Tumors

    • Local if possible, general if necessary.
    • Avoid sedatives/opioids.
    • AFOI with armored tube is the safest plan for airway.
    • Semi-Fowlers position.
    • Airway exam prior to extubation to ensure bilateral cord movement.
    • CPB equipment on standby.

    Thyroid Surgery Complications

    • Morbidity near 13%.

    RLN injury:

    • Can be unilateral or bilateral and can be temporary or permanent.
      • Unilateral: hoarseness, usually only for 3-6 months, but can be permanent.
      • Bilateral: absent vocal cord function, may require tracheostomy.

    SLN injury:

    • Results in weakening of voice.

    Hypoparathyroidism:

    • Damage to blood supply → hypocalcemia in first 24-48h postop.
      • Stridor can occur, which can develop into a laryngospasm.
      • Tracheal compression 2/2 hematoma.

    Parathyroid Glands

    • Four glands that secrete PTH, which regulates calcium concentration.
    • Secretion of PTH is inversely related to plasma calcium concentration.
    • Functions:
      • Promotes mobilization of bone calcium.
      • Enhances conversion of vitamin D to active form which increases Gl absorption of Ca2+.
      • Increase renal tubular absorption of calcium.
      • Inhibits renal absorption of phosphate.

    Primary Hyperparathyroidism

    • Results from excessive secretion of PTH 2/2:
      • Benign PT adenoma.
      • Carcinoma of PT.
      • Hyperplasia of the PT.
    • Most common cause of hypercalcemia in the general population.
    • Cancer is the most common cause in hospitalized patients.
    • Tx: Removal of PT glands → expect [Ca] to normalize in 3-4 days.
    Signs & Symptoms of Hyperparathyroidism
    NM
    Renal
    Blood
    Cardiac
    GI
    Skeletal
    Nervous

    Parathyroidectomy postoperative concerns

    • Postoperative tetany 2/2 hypocalcemia.
    • Transient hyperchloremic metabolic acidosis can occur 2/2 deteriorating renal function.

    Anesthetic Management of Primary Hyperparathyroidism

    • No evidence that any medications or techniques are necessary in the patient with primary hyperparathyroidism.
    • Maintenance of hydration and urine output are important.
    • Take care with positioning and padding → weakened bones.
    • Coexisting muscular weakness may suggest a reduced requirement for muscle relaxation, but hypercalcemia can antagonize the effects of NDMR.
    • Monitor for EKG changes.

    Secondary Hyperparathyroidism

    • Compensation for a pathology that leads to hypocalcemia.
    • Seldom leads to hypercalcemia.
    • Treatment directed towards normalizing serum phosphate in patients with renal disease by administering a phosphate binder, orally.

    Hypoparathyroidism

    • Pathology:
      • Secretion of PTH is absent.
      • Secretion of PTH is deficient.
      • Peripheral tissues are resistant to effects of PTH.
    • Almost always iatrogenic, occurring with inadvertent removal of PT during thyroidectomy.
    • DX: Hypocalcemia with low or inappropriately normal PTH hormone and hyperphosphatemia.
    • S&S: variable depending on the onset of hypocalcemia.
    • TX: Calcium gluconate or calcium chloride.

    Anesthetic Management of Hypoparathyroidism

    • Prevent further decreases in calcium and treat adverse effects of hypocalcemia.
    • Hyperventilation and admin of bicarb can decrease calcium.
      • Blood products containing citrate will not typically decrease calcium concentrations.
      • lonized calcium can decrease with blood transfusions are rapid (500mL every 5-10min) as seen in CPB or liver transplant.

    The Pituitary Gland: The Master Gland

    • Bilobed body located beneath the hypothalamus.
    • Divided into anterior and posterior segments.
    Pituitary Hormones Cell Type Principal Action
    Anterior Pituitary
    Human growth hormone (somatotropin) Somatotropes Accelerates body growth; insulin antagonism
    Prolactin Lactotropes Stim secretion of milk and maternal behavior; inhib ovulation
    Luteinizing hormone Gonadotropes Stim ovulation in females; stim testosterone secretion in males
    Follicle-stimulating hormone Gonadotropes Stim ovarian follicle growth in females; spermatogenesis in males
    Adrenocorticotrophic hormone Corticotropes Stim adrenal cortex section and growth; steroid production
    Thyroid-stimulating hormone Thyrotropes Stim thyroid secretion and growth
    b-Lipotropin Corticotropes Precursor of endorphins
    Posterior Pituitary
    Arginine vasopressin Supraoptic nuclei Promotes water retention and regulates plasma osmolarity
    Oxytocin Paraventricular nuclei Causes ejection of milk and uterine contraction

    Anterior Pituitary

    • GH: stimulates growth of all tissues in the body and causes intense metabolic effects.
      • Excess secretion leads to gigantism, but with excess secretion after closure of epiphyseal growth plates, acromegaly occurs.
    • Prolactin: stimulated release can occur with stress, but also with pregnancy and some drugs (metoclopramide, cimetidine, opioids, methyldopa).
    • ACTH: regulates cortisol and androgens.
      • Cushing Syndrome - overproduction of ACTH.
    • TSH: accelerates the formation of thyroid hormones.

    Posterior Pituitary

    • Reservoir for AVP and oxytocin.
      • AVP synthesized in supraoptic nuclei.
      • Oxytocin synthesized in paraventricular nuclei.
    • Destruction of neurons in or near the supraoptic and paraventricular nuclei of the hypothalamus from surgery on the pituitary, trauma, cerebral ischemia, or malignancy can decrease production/release of AVP → Diabetes insipidus.
      • Opposite is SIADH → dilutional hyponatremia that occurs from head injury, tumors, meningitis, and certain infections.
    • Assess urine specific gravity.

    Anterior Pituitary Disorders

    • Acromegaly: too much growth hormone.
      • Most often an adenoma in the anterior pituitary.
    • S&S:
      • Skeletal overgrowth: prognathism.
      • Soft tissue overgrowth: lips, tongue, epiglottis, vocal cords.
      • Connective tissue overgrowth: RLN paralysis.
      • Visceromegaly.
      • Glucose intolerance/DM.
      • Osteoarthritis.
      • Osteoporosis.
      • Hyperhidrosis.
      • Skeletal muscle weakness.
      • Peripheral neuropathies are common due to nerve entrapment.
      • Increased incidence of hypertension, ischemic heart disease.

    Treatment:

    • Preferred initial therapy is transsphenoidal resection of the pituitary.
    • If adenoma extends beyond the sella turcica into other structures often surgery/radiation are not feasible and long-acting somatostatin is used.

    Anesthetic Management of Acromegaly

    • Airway is of primary concern:
      • Facial distortion can make mask ventilation difficult.
        • Tongue and epiglottis enlargement interfere with visualization of larynx.
          • Preop history of dyspnea on exertion or presence of hoarseness/stridor suggest laryngeal involvement.
          • Could have a narrower glottic opening due to overgrowth of cartilage → may require smaller tube than predicted.
        • Turbinate enlargement can make nasopharyngeal placement of ETT or G tube more challenging.
        • If difficult intubation is predicted, an awake fiberoptic approach should be considered.
      • Due to tissue overgrowth, the ulnar artery could be compressed → radial artery catheterization could be detrimental.
    • Glucose monitoring is a priority.
    • NO evidence that hemodynamic instability or alterations to gas exchange occur with acromegaly (acromegaly in isolation).

    Posterior Pituitary Disorders

    Diabetes Insipidus: not enough ADH

    • Absence of vasopressin (ADH) due to:
      • Destruction of posterior pituitary → neurogenic DI.
      • Failure of renal tubules to respond to ADH → nephrogenic DI.
    • Dx: polydipsia and high output of dilute urine despite increased osmolality.
    • Transient type occurs following pituitary surgery secondary to trauma to the posterior pituitary.
    • Tx: oral intake initially, then IV infusions of electrolytes and fluids.
      • Neurogenic: desmopressin → available IC, PO, and intranasal.
      • Nephrogenic: low-sodium, low-protein diet, diuretics, and NSAIDs.
    • Anesthesia management: monitor UOP and electrolyte concentrations.

    SIADH: too much ADH

    • Common causes include:
      • Tumors.
      • Hypothyroidism.
      • Porphyria.
      • Lung carcinoma.
    • Inappropriate secretion of ADH occurs during/following major surgeries.
    • Dx: increased urinary sodium and osmolality + decreased serum sodium and osmolality.
    • Tx: fluid restriction, high solute intake, salt tablets.
      • Diuretics.
      • Vasopressin receptor antagonists.
        • Demeclocycline.
      • IV hypertonic saline for those resistant to treatment.

    Adrenal Glands

    • Adrenal cortex secretes three major classes of corticosteroids:
      • Mineralocorticoids.
      • Glucocorticoids.
      • Androgens.
    • Precursor of all corticosteroids is cholesterol.
    • Divided anatomically into three zones:
      • Zona glomerulosa - secretes mineralocorticoids.
      • Zona fasciculata - secretes glucocorticoids.
      • Zona reticularis - secretes androgens and estrogens.

    Zona Glomerulosa: Mineralocorticoids

    • Primarily aldosterone - 95%.
      • Increases ECF volume via the increase reabsorption of sodium and thus water.
      • Also decreases potassium concentration.
      • Secretion is stimulated via increased potassium concentration and function of the RAAS.
      • Mineralocorticoid activity is not regulated by ACTH.

    Zona Fasciculata: Glucocorticoids

    • Primarily cortisol - 95%.

    • Functions:

      • Developmental changes: increase during pregnancy to maximize fetal development to survive extrauterine life.
      • Gluconeogenesis: 10X effect; accelerated rate can cause adrenal diabetes.
      • Protein catabolism: breakdown protein stores in all tissue other than liver for the purpose of gluconeogenesis.
      • Fatty acid metabolism: adrenal dysfunction can lead to "buffalo hump" buildup of fat.
      • Anti-inflammatory Effects: stabilized liposomal membranes and decreases WBC migration to areas of inflammation.

    • Perioperative stress will increase ACTH and cortisol release → peaks with NMBA reversal and Extubation.

      • A deep extubation or avoiding the ETT in the first place (regional anesthesia) can decrease this response, but not eliminate
      • Must accommodate patients who take exogenous steroids!### Pheochromocytoma

    • Catecholamine-secreting tumor, typically found in the adrenal medulla

    • Accounts for 0.1% of hypertension in adults, but carries a high mortality risk

    • Diagnosis is imperative due to high mortality risk

      • 24-hour urine collection to measure plasma-free metanephrine and metanephrine levels.
      • Plasma-free metanephrine > 400 pg/mL
      • Metanephrine > 220 pg/mL

    • Symptoms include hypertension, sweating, headache, and anxiety

    • Less common symptoms encompass abdominal pain, nausea, vomiting, diarrhea, pallor, hallucinations, agitation, apprehension, tremor

    • Pre-operative management is essential for successful treatment

    • Alpha blockade is crucial

      • Lowers blood pressure
      • Increases intravascular volume
      • Prevents hypertensive episodes
      • Adrenergic receptor sensitization
      • Decreases myocardial dysfunction

    • Beta-blockade may be used in select patients with tachycardia

      • Never give non-selective beta blockers before alpha blockers

    • Metyrosine inhibits tyrosine hydroxylase, reducing catecholamine production

      • Can cause sedation and extrapyramidal side effects

    • Intra-operative management requires optimal preparation, including alpha blockade, beta-blockade, and correction of hypovolemia

    • Avoidance of drugs or maneuvers that trigger catecholamine release is paramount

      • Reduce and prevent fear, stress, pain, shivering, hypoxia, and hypercarbia

    • Intra-operative blood pressure control relies on short-acting agents

      • Arterial line and central venous pressure monitoring are recommended
      • Hypotension is common after ligation of the pheochromocytoma
      • Hypertension is common during pneumoperitoneum
      • Sodium nitroprusside is the preferred agent for hypertension
      • Phentolamine is effective, but associated with tachyphylaxis and tachycardia
      • Nitroglycerin can lead to tachycardia
      • Labetalol is preferred for tumors primarily secreting epinephrine
      • Magnesium sulfate decreases catecholamine release and reduces receptor sensitivity
        • Refractory hypertension may require a combination of sodium nitroprusside, esmolol, diltiazem, and phentolamine

    • Arrhythmias are typically ventricular, treated with beta blockers and/or lidocaine

    • Post-operative management includes monitoring for hypoglycemia and hypertension

    • Hypovolemia is the most common cause of death in the immediate postoperative period

    • Patients may require large volumes of fluids and vasopressors

    Cushing Syndrome

    • Characterized by excessive cortisol production
    • Can be ACTH-dependent or ACTH-independent
    • Symptoms include central weight gain, hypertension, glucose intolerance, and skeletal muscle weakness
    • Diagnosis involves measuring cortisol concentration in a 24-hour urine sample.
    • Treatment includes transsphenoidal microadenomectomy or resection of the anterior pituitary

    Conn Syndrome

    • Characterized by excessive aldosterone production from an adenoma
    • Associated with pheochromocytoma, hyperparathyroidism, and acromegaly
    • Symptoms include hypertension, headache, polyuria, nocturia and muscle weakness
    • Diagnosis involves spontaneous hypokalemia with systemic hypertension
    • Treatment includes potassium supplementation, aldosterone antagonists, and surgical excision of the secreting tumor.

    Anesthetic Management:

    • Pre-operative correction of potassium and treatment of hypertension are essential
    • Hyperventilation should be avoided, as it can decrease potassium levels further
    • Pulmonary artery catheter and transesophageal echocardiogram may be necessary for accurate hemodynamic monitoring
    • Exogenous cortisol administration may be required.

    Addison's Disease

    • Primary adrenal insufficiency results in the inability to produce cortisol, aldosterone, and androgen hormones
    • Secondary adrenal insufficiency occurs due to failure to produce corticotropin-releasing hormone or ACTH
    • Diagnosis involves measuring baseline plasma cortisol levels and cortisol levels after ACTH stimulation
    • Treatment involves exogenous steroid administration
    • Patients on chronic steroid therapy are unable to produce their own cortisol during times of stress, requiring a "stress dose" of hydrocortisone (100-200 mg)
    • A five-day course of steroids decreases cortisol production for five days following discontinuation.

    Anesthetic Management:

    • Treat hemodynamic instability if present
    • Administer 100 mg hydrocortisone every six hours
    • Correct volume deficits, which can be substantial.

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    NA 731 Endocrine Pathophysiology PDF (Fall 2022)

    Description

    Test your knowledge on pheochromocytoma, its treatment, and related endocrine disorders such as Cushing Syndrome and Addison's Disease. This quiz covers various aspects of these conditions, including symptoms, diagnosis, and surgical considerations. Perfect for students and healthcare professionals seeking to enhance their understanding.

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