Thyroid and Adrenal Glands Flashcards
Enlargement of the Thyroid gland is called what?
Thyroid goiter
What is absorbed in the GI track and incorporated into T3 and T4 as thyroglobulin?
Iodine
What releases the stimulating factors/hormones for the thyroid gland?
Release of hormone occurs by Hypothalamic – Pituitary interaction
Interactions among the hypothalamus, the pituitary gland, and the adrenal (also called “suprarenal”) glands, (HPA axis) is a major part of the neuroendocrine system that controls reactions to ____ and regulates many body processes.
reaction to stress
Which of the following are regulated by the HPA axis?
A. Digestion B. The immune system C. Mood and emotions D. Sexuality E. Energy storage and expenditure F. All of the above
F
What links the nervous system to the endocrine system via the pituitary gland?
hypothalamus
How does the hypothalamus affect the thyroid gland
It secretes TRH, which is produced by the hypothalamus.
What is TRH?
Thyrotropin-releasing hormone (TRH), also called thyrotropin-releasing factor (TRF), a hormone that stimulates the release of TSH (thyroid-stimulating hormone) and prolactin from the anterior pituitary.
Some people develop antibodies against their own TSH receptors. When these bind the receptors, they “fool” the cell into making more T4 causing hyperthyroidism. The condition is called_______.
thyrotoxicosis or Graves’ disease.
The secretion of TSH is
stimulated by ___ and inhibited ___.
The secretion of TSH is
stimulated by the arrival of thyrotropin releasing hormone (TRH) from the hypothalamus.
inhibited by the arrival of somatostatin from the hypothalamus.
TSH stimulates the thyroid gland to secrete its hormone_______ .It does this by binding to transmembrane _______on the surface of the cells of the thyroid.
thyroxine (T4)
G-protein-coupled receptors (GPCRs)
A deficiency of TSH causes ______: inadequate levels of______.
hypothyroidism, T4 (and thus of T3)
____ is more metabolically active and formed peripherally by de-iodination of ___.
triiodothyronine (T3) is more metabolically active and formed peripherally by de-iodination of thyroxine (T4)
_____ is necessary for the production of T3 and T4. A deficiency leads to _____ production of T3 and T4, enlarges the _____ and will cause the disease known as ____.
Iodine
leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as goitre.
The major form of thyroid hormone in the blood is ____, which has a longer half-life than___. The ratio of __to released into the blood is roughly 20 to 1.
thyroxine (T4),which has a longer half-life than T3. The ratio of T4 to T3 released into the blood is roughly 20 to 1.
T or F. If there is a deficiency of dietary iodine, the thyroid will not be able to make thyroid hormone.
True
The lack of thyroid hormone will lead to _______ negative feedback on the pituitary, leading to ______ production of thyroid-stimulating hormone, which causes the thyroid to ____.
decreased negative feedback on the pituitary
increased production of TSH
enlarge (the resulting medical condition is called endemic colloid goiter
What causes the thyroid gland to enlarge and what effect does this have?
a deficiency of dietary iodine-> thyroid unable to make thyroid hormone->lack of thyroid hormone -> goiter
This has the effect of increasing the thyroid’s ability to trap more iodide, compensating for the iodine deficiency and allowing it to produce adequate amounts of thyroid hormone.
What limits the thyroid hormones peripheral function?
Thyroid hormones are extensively protein bound limiting their peripheral function
List 5 functions of the thyroid hormone.
Thyroid Hormone
Increases carbohydrate and fat metabolism
Is important for growth
Is important for stress response
It increases metabolic rate
Increased adrenergic-receptor responsibility
How does thyroxine (T4) effect each of the following:
Cardiac Output
Heart Rate
Ventilation Rate
Basal Metabolic Rate
Increases all of them
T or F. T4 Potentiates the effects of catecholamines (i.e. increases sympathetic activity)
True
t or f . Tyroid hormones increase the body’s sensitivity to catecholamines (such as adrenaline) by permissiveness.
True. Thyroid hormone increases the number of receptors available for epinephrine at the latter’s target cell, thereby increasing epinephrine’s effect on that cell. Without the thyroid hormone, epinephrine would have only a weak effect
Permissiveness is a biochemical phenomenon in which ______ is required for _____.
the presence of one hormone is required in order for another hormone to exert its full effects on a target cell
What are the three cardiac effects of hyperthyroidism? Why are these common?
Tachycardia
Atrial fibrillation
Congestive heart failure
Common bc these pts are hyper-sensitized to catecholamines
The following are characteristic of what endocrine disease?
Muscle weakness Nervousness Hyperactive reflexes Weight loss Heat intolerance Tremor
Hyperthyroidism
What are three ways to treat hyperthyroidism?
Inhibit Synthesis
Prevent Release
Block the End Results
What two drugs can be used to inhibit the synthesis of thyroid hormone?
Propylthiouracil and methimazole
What are two things that can be taken to prevent the release of thyroid hormone?
Potassium Iodide or Sodium Iodide
One way to treat hyperthyroidism is to block the end results of the thyroid hormone. What class of drugs is used to do this?
Block the End Results w/ Beta-blockers. This is what we do.
List 3 things that are required to render a patient w/ a known hx of hyperthyroidism as euthyroid they present for an elective case.
elective cases should be rendered euthyroid
Normalization of TFT’s (want T3/T4 brought down, and TSH brought up to normal levels)
Heart rate < 85 / min
Continue medications on morning of surgery
List the 6 intra-op anesthetic considerations for hyperthyroid patients.
Protect Eyes Close monitoring of CV system Accurate temperature monitoring Avoid sympathetic stimulating drugs (Ketamine, Pancuronium) Likely hypovolemic and vasodilated Be careful with muscle relaxants
What are the 4 indications of a Thyroid Storm?
Hyperpyrexia
Tachycardia
Mental Status Changes
Hypotension
T or F. Thyroid Storm mimics MH, including muscle rigidity, and lactic acidosis
False. it mimics MH but the difference is that with Thyroid storm, there is
No muscle ridgidity
No lactic acidosis
T or F. Thyroid Storms can occur intra-op or post-op, but they most commonly occur intra-op.
False. Most commonly occurs 6-24 hrs post-op
How do you treat a Thyroid Storm?
Volume replacement
Control Cardiovascular system
Block Thyroid hormone release
What is the “Paper Test” ?
Used on hyperthyroidism pts - i u put there ares straight out in front of them, and put a piece of paper on the back their hands, it will shake right off of them.
T or F. Hypothyroidism is characterized by weight loss despite increased appetite.
False. That is hyperthyroidism
Low LDL, diarrhea, brisk reflexes and osteoporosis is seen in what thyroid disease
Hyperthyroidism
What is the most common reason for hyperthyroidism?
Graves Disease (or thyrotoxicosis) - develop antibodies against their own TSH receptors. When these bind the receptors, they “fool” the cell into making more T4 causing hyperthyroidism. The condition
What is Hot Adenoma? What does it cause?
It is a functional thyroid tumor, producing excessive thyroid hormone - Causes hyperthyroidism
What is Factitious hyperthyroidism? What type of patients are susceptible to this?
Factitious or iatrogenic hyperthyroidism is due to an exogenous intake of thyroid hormone. This happens when hypothyroid pts take too much thyroid supplements.
What are the 4 common causes of hyperthyroidism
Graves Disease
Hot Adenomas
Factitious
Scondary
What is secondary hyperthyroidism
Secondary hyperthyroidism, or TSH-mediated hyperthyroidism, is caused by too much TSH release. It is always associated with goiter, and approximately 40% of patients have visual field defects
T or F. Hyperthyroidism is a metabolic up-regulation causes an up-regulation of all systems.
False. The brain is not up-regulated. mental confusoin, Depression, Apathy, and dementia are associated with hyperthyroidism.
What is hypothyroidism?
hypothyroidism (‘sluggish thyroid’), which is the reduced production and secretion of T3 and/or T4
T or F. A wide pulse pressure is associated with hypothyroidism.
False. Hyperthyroidism
T or F. In primary hyperthyroidism, T3 and T4 levels are very high and TSH levels are very low, almost undetectable
True
T or $. You need to be careful with NMB with hyperthyroid pts bc they will have prolonged neuromuscular blockade.
True
Why do you want to avoid drugs that rev up the sympathetic system/ vagolytic drugs in pts with hyperthyroidism? Name some to avoid.
They are already revved up and will have an exaggerated response. This can lead to arrhythmias
Avoid Ketamine, pancuronium, and indirect sympathomimetics
What disease is characterized by exophthalmos (bulging of the eyes) and lid retraction, making them more susceptible to corneal abrasions during surgery?
Graves Disease
What is Hashimoto’s thyroiditis?
Hashimoto’s thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disease in which the thyroid gland is attacked by a variety of cell- and antibody-mediated immune processes. very often results in hypothyroidism with bouts of hyperthyroidism. Symptoms of Hashimoto’s thyroiditis include Myxedematous psychosis, weight gain, depression, mania, sensitivity to heat and cold, paresthesia, fatigue, panic attacks, bradycardia, tachycardia, high cholesterol, reactive hypoglycemia, constipation, migraines, muscle weakness, joint stiffness, menorrhagia, cramps, memory loss, vision problems, infertility and hair loss.
T or F. Goiters can result from both hypo and hyperthyroidism.
True
Airway compromise associated with thyroid diseases include what?
Airway Compromise Goiter Strider Hematoma Pneumothorax
What causes stridor in patients with goiters of they thyroid gland.
pressure on the recurrent laryngeal nerve
What is the major anesthetic consideration associated with hypothyroid?
Myxedema Coma - a state of decompensated hypothyroidism. The patient may have lab values identical to a “normal” hypothyroid state, but a stressful event (infections, MI, stroke, drugs, etc.) precipitates the myxedema coma state, usually in the elderly. Primary symptoms of myxedema coma are altered mental status and hypothermia. Hypoglycemia, hypotension, hyponatremia, hypercapnia, hypoxia, bradycardia, and hypoventilation may also occur.
The following are characteristic of what thyroid state?
Weak heart beat
slowing of mind and body
cold intolerance
hypothyroidism
Why is surgery on the adrenal glands challenging? What approach has made it easier.
Because they are located in the retro-peritoneal space on top o the kidneys. Laparoscopic
The adrenal glands are responsible for releasing hormones in response to stress through the synthesis of ________ such as cortisol and ______ such as epi and NE, and _______ such as aldosterone.
corticosteroids
catecholamines
androgens.
The adrenal glands affect kidney function through the secretion of ________, a hormone involved in regulating the osmolarity of blood plasma.
aldosterone
T or F. The Adrenal Medulla receives input from the sympathetic nervous system and secretes catecholamines directly into the blood.
True
Pheocromocytomas develop where
Adrenal medulla cells
Catecholamines are derived from ______ and are _____ soluble..
the amino acid tyrosine , water soluble
All of the hormones from the adrenal cortex are derived from ________.
cholesterol
T or F. The Hormones of the adrenal cortex bind to cell membranes to G-protein-coupled receptors (GPCRs).
False. They are lipid soluble and act inside the nucleus where they upregulate or down regualte gene transcription
T or F. Steroid hormones act quickly like catecholamines
False. Catecholamines bind to surface receptors and exert their effect immediately but, steroid hormones penetrate through the cell membrane and the nuclear membrane and impact DNA transcription…much slower process
T or F. Aldosterone is a steroid hormone produced in the adrenal medulla.
False it is a steroid hormone produced in the adrenal cortex
How does Aldosterone effect fluid and electrolytes?
Regulates fluid and electrolyte balance
Increases Na+ reabsorption from Distal Tubules
Retention of Na+ leads to water retention
A tumor that releases too much ACTH will have what effect?
hyperaldosterone state
When blood pressure fall, it is sensed by maculla densa cells in the distal tubules of the nephron, who then secrete _____.
Renin
The_____ enzyme circulates in the blood stream and breaks down (hydrolyzes) ________ secreted from the liver into the peptide _________.
Renin, angiotensinogen, angiotensin I
________ is further cleaved in the lungs by endothelial-bound angiotensin-converting enzyme (ACE) into _______, the most vasoactive peptide.
Angiotensin I, angiotensin II
Angiotensin II is a potent ______ of all blood vessels. Angiotensin II also acts on the adrenal glands, causing the release ______.
constrictor, Aldosterone
Which of the following stimulates the synthesis of Aldosterone?
A. Increase in plasma angiotensin II B. ACTH C. potassium levels D. A and B E. All of the above
E
T or F. Exposure to cold leads to increased cortisol levels.
True
What 3 things are secreted by the adrenal cortex?
Androgens
Glucocorticoids
Aldosterone
T or F. Aldosterone upregulates epithelial sodium channels, leading to an increased number of Na channels allowing increased permeability for Na+.
True
How do glucocorticoids promote energy storage?
- Promote gluconeogenesis
- Decrease peripheral utilization of glucose
T or F. Glucorticoids have insulin like effects?
False. Anti-insulin Effects. cortisol stimulates several processes that collectively serve to increase and maintain normal concentrations of glucose in blood
T or F. Glucocorticoids are required for smooth muscle response to catecholamines.
True
T or F. When you have high levels of glucorticoids, it can cause Na retention.
True
Glocorticoids have effect on which of the following:
A. Muscle
B. Fat Cells
C. Liver
D. All of the above
D
T or F. In attempt to preserve glucose, glucocorticoids stimulate lipolysis.
True
T or F. Androgens greatly impact anesthetic management.
false
List the 7 symptoms of Pheochromocytomas
Hypertension Paroxysmal headache Sweating Palpitations Tachycardia Weight Loss Heat Intolerance
T or F. Pheochromocytomas are only generated in the adrenal medulla.
False. They can be generated any where along Sympathetic Ganglion Cell or anywhere they have Neuroblastoma
cells - can be scattered throughout abdominal cavity or up and down their spine
Stimulation of which Adrenergic receptor causes each of the following:
A. ↑lipolysis
B. ↑renin secretion
C. ↑glycogenolysis
D. ↓ insulin secretion
A. ↑lipolysis = B1 and B3
B. ↑renin secretion = B1
C. ↑glycogenolysis = B2
D. ↓ insulin secretion = A2
T or F. Patients who have a pheo are hypertensive and hypervolemic.
F. They are hypertensive, but the andrenergic stimulation causes natural diuresis to try to bring down the BP and these pts are often hypovolemic
Which of the following are involved with managing a pt with a pheo
A. Alpha blockade
B. Beta blockade
C. Fluid
D. All of the above
D
Why are you often dealing with hypotension following ligation of adrenal vein drainage?
Due to removal of catecholamines
Excess treatment of hypertension
Inadequate fluid resuscitation
What disease is characterized by the following:
Excessive aldosterone release Increased blood pressure Hypervolemia Hypokalemia Muscle Weakness Metabolic Alkalosis
Aldosteronoma - also called Conn’s syndrome
HTN + hypoK —> think Aldosteronoma
What disease is characterized by the following:
Muscle Wasting Osteoporosis Central Obesity Abdominal Striae Glucose Intolerance Hypertension Mental Status Changes Buffalo Hump
Cushing’s Syndrome
How do you treat Aldosteronoma?
Spironolactone (diuretic)- inhibit Na reabsorption, causes K retention or remove tumor causing it
T or F. High levels of Aldosterone are seen in Cushing’s patients
True
What causes Cushing’s Syndrome?
either a tumor in the adrenal gland that causes over production of cortisol OR a tumor in the pituitary gland that causes the unregulated release of ACTH (70%)
What does ACTH stand for ?
adrenocorticotropic hormone (ACTH)
What is the difference bn Cushings syndrome and Cushings disease
Cushing’s syndrome refers to excess cortisol of any etiology
primary hypercortisolism/hypercorticism - cortisol secreting adenoma in the cortex of the adrenal gland - The adenoma causes cortisol levels in the blood to be very high, and negative feedback on the pituitary from the high cortisol levels causes ACTH levels to be very low.
Cushing’s disease refers only to hypercortisolism secondary to excess production of ACTH from a corticotroph pituitary adenoma (secondary hypercortisolism/hypercorticism) or due to excess production of hypothalamus CRH (Corticotropin releasing hormone) (tertiary hypercortisolism/hypercorticism). This causes the blood ACTH levels to be elevated along with cortisol from the adrenal gland. The ACTH levels remain high because the tumor is unresponsive to negative feedback from high cortisol levels.
When Cushing’s Syndrome is suspected, what diagnostic test is used and how does it work?
dexamethasone suppression test - administration of dexamethasone at midnight and measure cortisol and ACTH levels 12 hrs later. Dexamethasone is a glucocorticoid and simulates the effects of cortisol, including negative feedback on the pituitary gland, leading to low ACTH and cortisol levels. If the cortisol levels are high, this indicates the presence of a non-regulating tumor such as adrenal or pituitary adenoma that is not inhibited by the dexamethasone - thus would be indicative of Cushing’s syndrome.
What do we see in Cushing patients.
Fluid Overloaded Hypokalemia Metabolic Acidosis Risk for Fractures - osteoporosis Muscle Weakness – Prolonged Paralysis Stress Intolerance
Do Cushings pts require stress dose of steroids for surgery? if so what is the dose
yes. Hydrocortisone replacement 100 mg q8
The following are characteristic of what disease?
Destruction of the adrenal gland Hyponatremia Hypotension Hyperkalemia Weight Loss
Addison’s Disease
A patient is hyperkalemic but does not have kidney problems. What could explain this?
Addison’s Disease
Why is a stress dose of hydrocortisone 100 mg q8 if we normally only secrete 20mg of cortisol a day?
In a stress state (surgery) we can secrete up to 300 mg a day. So 100mg q8 = 3*100.
T or F. A patient who has been in the ICU for a prolonged period of time is usually adrenally suppressed ad will need a stress dose of steroids.
True
T or F. A burn patient who has received multiple doses of etomidate for all of their dressing changes may require a stress dose of steroids.
True. Multiple doses of etomidate causes adrenal supression
