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.