Download Understanding The Thyroid: What It Is and What It Does

Jean A. Trost, RN, BSN
Alverno College – MSN 621
May 2010
Start
By the end of this tutorial, you will be able to:
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Demonstrate accurate knowledge involving the
pathophysiology of hyper-/hypothyroidism
Have basic knowledge of treatments for hyper/hypothyroidism
Have accurate knowledge of the signs and symptoms of
the disease process of hyper-/hypothyroidism to include
the effects of thyroid disease on the patient population
Be able to effectively teach the patient population the
differences between hyper-/hypothyroidism
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Use the following buttons to help you
navigate
To advance forward click the left mouse key
or the enter key
To move backward one slide
To end the tutorial
To go to the home page
To hyperlink segment (click on “Thyroid
Gland and Negative Feedback”) H
Hyoid Bone
Cricothyroid Ligament
Largest Endocrine Gland
(Weight 20-25g—just
under one ounce)
http://www.ohsubooks.com/objectives/images/6/6c/Thyroid.jpg
(Martini, F., 1992)
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Arises from the root of the embryonic tongue (located on the
back of tongue) and descends into the neck
Is wrapped around the anterior and lateral aspects of the
trachea right below the larynx
Consists of two large lobes, one on each side of the trachea,
connected by a narrow anterior isthmus
(Martini, F., 1992)
http://www.abc.net.au/health/library/img/thyroid_gland_diag.gif
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The thyroid is composed mostly of sacs called thyroid follicles
A network of capillaries, which accept secretory products and
metabolic wastes and deliver nutrients and regulatory
hormones to the glandular cells, surrounds each follicle
Each follicle is filled with a protein-rich colloid and is lined
with a simple cuboidal epithelium of follicular cells, which
aids in secretion
(Matfin, Porth, 2009)
http://biology.clc.uc.edu/fankhauser/Labs/Anatomy_&_Physiology/A&P202/
Endocrine_System/histology_jpgs/thyroid_400x_P2252255lbd.JPG
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Thyroid follicles release several hormones into the circulation
These hormones are derivatives of the amino acid tyrosine to
which 3 or 4 iodine atoms have been attached
(Goodson, no date provided)
http://www.anaesthetist.com/icu/organs/endocr/thyroid/images/t3t4.gif
•Larynx
•Right Lobe
•Left Lobe
•Isthmus
•Trachea
•Thyroid Follicle
Larynx
Left lobe
Right lobe
Thyroid
follicle
Isthmus
Trachea
http://1.bp.blogspot.com/_4XalECA8LI8/SeqV6ClAzqI/AAAAA
AAAAIM/NQ10fthQwfY/s400/ethereal-Thyroid-Gland.jpg
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To control the rate and method of tissues’ utilization of food
and natural chemicals for creation of energy
To take iodine trapped in circulating blood and convert it to
thyroid hormones
To use the above energy in the creation of muscle energy and
body heat
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To combine iodine and the amino acid tyrosine to make
Thyroxine (T4), which contains 4 iodine atoms, and
Triiodothyronine (T3), which contains 3 iodine atoms and
possess four times the hormone strength of T4
The normal thyroid gland produces 90% T4 cells and 10% T3
cells
T3 and T4 are released into the blood and transported
throughout the body where they control metabolism—the
conversion of oxygen and calories to energy
(Matfin, Porth, 2009)
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T3 and T4 have complimentary effects
◦ T3 produces a strong, immediate, and temporary increase in cellular
metabolism
◦ T4 slowly and gradually diffuses into peripheral tissues and produces a
long-term response
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T4 is converted to T3 in the cytoplasm of the cell; thus, the
effects of T3 and T4 are the same
(Matfin, Porth, 2009)
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Raises the
circulating
 Incorrect
 concentration
The parathyroid gland
raises blood
of (PTH)
calcium
calcium levels when needed
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The thyroid gland increases the metabolic rate,
which in turn creates energy
 Correct
Regulates growth
and development
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The thyroid gland regulates growth and
development
Correct
To create energy
 Incorrect
To create
stomach acid
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The chief cells in the stomach create HCL
(stomach acid)
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Occurs as either an acquired or congenital
defect
Acquired hypothyroidism is related to either
primary disease of thyroid gland or to
disorders of the pituitary or hypothalamic
source and develops in later life
(Matfin, Porth, 2009)
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Loss of appetite
Chronic
fatigue/Tiredness
Constipation
Depression
Dry skin/other skin
conditions
Hair loss
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Infections
Sensitivity to cold/low
body temperature
Muscle weakness
Weight gain
Painful/heavy
premenstrual period
Slow speech
(Matfin, Porth, 2009)
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Treatment:
 Thyroid function improves with:
◦ Proper balance of nutrients
◦ Thyroid hormone replacement medication
 Synthroid/levothyroxine/levoxyl/levothroid
Management:
 Follow up blood work to monitor TSH
(Thyroid Stimulating Hormone) levels
 Regular visits with M.D.
 Balanced nutrition
(Matfin, Porth, 2009)
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Incorrect
An increase in the metabolic rate creates
Increase
metabolic
process
increasedinenergy;
hypothyroid
activity
means the thyroid gland is not very active.
Therefore, the metabolic rate decreases
•Correct
•The thyroid gland’s job is to increase the
Decrease
in metabolic process
metabolic rate; hypothyroidism means the gland is
underactive and not working to create increased
energy
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Incorrect
The chief cells in the stomach create
hydrochloric
acid (HCl)
Increase
in stomach
acid
•Incorrect calcium in
Decrease
in
circulating
•The parathyroid gland monitors blood calcium
blood
levels
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Occurs when tissues are exposed to elevated
levels of circulating hormone
Hyperactivity of thyroid gland which increases
metabolism (overactive thyroid gland)
http://www.patient.co.uk/images/OM934a.jpg
(Moore, no date provided)
http://www.meddean.luc.edu/lumen/MedEd/Medicine/
pulmonar/pdself/Goiter1.jpg
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Hypoactivity of thyroid gland causes a
decrease in metabolic processes (underactive
thyroid gland)
Most common cause: Hashimoto thyroiditis
(an autoimmune disorder in which the thyroid
may be totally destroyed—a disease found
predominantly in women with a female to
male ratio of 5:1)
(Matfin, Porth, 2009)
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Most common:
◦ Graves disease (autoimmune disorder, abnormal
stimulation of thyroid gland TSH/receptor
antibodies)
◦ Multinodular goiter (swelling of the thyroid gland
related to inability to uptake iodine)
◦ Adenoma of thyroid gland
◦ Thyroiditis (iodine-containing agents can cause
hyperthyroidism)
(Goodson, Moore, no date provided; Matfin, Porth, 2009)
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Increased
anxiety/nervousness
Diarrhea
Hair loss
Hand tremors
Heat intolerance
Insomnia
Muscle weakness
Palpitations/
tachycardia
(Matfin, Porth, 2009)
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Shortness of breath
Excessive sweating
Bulging of eye
balls/abnormal
retraction of eyelids
and frequent blinking
Thin skin
Weight loss
Separation of nails
from nail bed
Treatment:
 Obtains reduced levels of thyroid hormone
◦ Eradication of thyroid gland (with radioactive dye,
surgical removal of gland, use of medication to reduce
thyroid function)
Management:
 Balanced nutrition
 Regular M.D. visits
 Follow up blood work to monitor TSH (Thyroid
Stimulating Hormone) levels
 If treated with medication, monitor specific
pharmacological levels
(Matfin, Porth, 2009)
Thyroid Storm: What is it?
Thyroid Storm:
•Is a crisis with high mortality rate
•Is a life threatening form of thyrotoxicosis (Over
activity of thyroid gland: excessive thyroid hormones
in blood, Graves disease)
Precipitating factors:
•Diabetic Ketoacidosis
•Infection
•Physical/emotional trauma
•Surgical manipulation of thyroid gland
Signs/Symptoms:
•High fever
•Tachycardia/chest pain
•Congestive heart failure
•Agitation
•Delirium
•Restlessness
(Matfin, Porth, 2009)
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Thyroid Storm: what do you
do?
Treatment:
•Rapid Diagnosis
•Cooling of the body (shivering response must be
prevented)
•General support
•IV fluids
•Glucose and electrolytes to be provided
•B-adrenergic blocking drugs (blocks effects of T4
on cardiovascular function)
•Glucocorticodids to be given to correct adrenal
insufficiency
(Matfin, Porth, 2009)
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•
Correct
This High
is reflective
of an overactive
thyroid gland
fever/high
body
that is overproducing thyroid hormone—
remember temperature
the job of the thyroid is to produce
energy
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Correct
Increased weight loss
An overactive thyroid gland creates an increased
metabolism; therefore, the body utilizes stored fat
(energy) to keep pace with the increased metabolic
rate, which results in weight loss
Incorrect
•
Hypothyroidism will cause a decrease in the
metabolicSlow
rate, which
slows metabolism
speech
(energy production is significantly decreased)
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Correct
Intolerance to heat
An overactive thyroid gland produces increased
energy, which creates excess heat from that
energy production, making people intolerant to
environmental heat
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Located below the thalamus just above the
brain stem
Controls the autonomic functions of the body
◦ Autonomic nervous system is the part of the
nervous system that affects:
 Glands
 Smooth and cardiac muscle
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There is no voluntary control
http://z.about.com/d/psychology
/1/5/C/hypothalamus.jpg
(Bowen, 2003)
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Produces thyroid releasing hormone (TRH)
which informs the pituitary gland to stimulate
thyroid stimulating hormone (TSH)
Is the “grand poobah”: regulates the body’s
thermostat by informing the pituitary gland at
what level the thyroid should be set
(Bowen, 2003)
http://i.ehow.com/images/a04/hb/iv/
troubleshoot-thermostat-800X800.jpg
http://www.brsparty.com/site_flash/
images/GrandPoobah160.jpg
Below the thalamus just
Correct
above the brain stem
Cerebral
Incorrect
cortex
Frontal
Incorrect
lobe
Cerebellum
Incorrect
•Incorrect
•The cerebral cortex is outer neural tissue of
Thought process
the cerebrum which controls memory,
attention, and thought process
•Correct
•The hypothalamus links the autonomic
Thermoregulation
nervous system
to the endocrine system via the
pituitary gland, which controls body
temperature
•Incorrect
movement
•VoluntaryMuscle
muscle activity
is controlled by the
central nervous system and the cerebellum
•Incorrect
•Eye movement to track objects is initiated by a
Eye movement
small cortical region of the frontal lobe of the
brain
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Is suspended from the hypothalamus and is
under its control
Secretes 6 principle hormones:
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Follicle stimulating hormone(FSH)
Luteinizing hormone (LH)
Adrenocorticotropic hormone (ACTH)
Growth hormone (GH)
Thyroid stimulating hormone (TSH)
Prolactin (PRL)
(Matfin, Porth, 2009; Bowen, 2003)
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Hormonal relationship between the pituitary
gland and the hypothalamus (“grand poobah”)
and the thyroid gland creates a negative
feedback loop to maintain homeostasis
1) Hypothalamus secrets thyroid
releasing hormone—
thyrotropin releasing
hormone (TRH)
2) Then TRH stimulates anterior
pituitary to secrete TSH
3) The TSH will then stimulate
the thyroid gland to secrete
T3 and T4
(Matfin, Porth, 2009; Bowen, 2003)
4) T3 and T4
stimulate
metabolism of
most cells in body
5) T3 and T4 also
inhibit the release
of TSH by the
pituitary gland
6) T3 and T4 will
inhibit the release
of TRH by the
hypothalamus
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Steps 5 and 6 are negative feedback inhibition of the pituitary
and hypothalamus
This ensures that when the TH levels are high, TSH secretion
remains low
If TH levels drop, then TSH secretion climbs and stimulates
the thyroid to secrete more TH
This negative feedback loop helps to ensure that TH levels
remain at a typical homeostatic state
(Matfin, Porth, 2009; Bowen, 2003)
H
Hyperlink: http://biologyinmotion
.com/index.html
http://www.mirage-samoyeds.com/health/fig1a.gif
Central Nervous system
Neurochemical stimuli
Hypothalamus
Releases (TRH)
Anterior Pituitary
Positive feedback
Releases (TSH)
Thyroid Gland
Stimulates the release of T3 &T4
Negative feedback loop
T3
T3 & T4 stimulate metabolism
T4
T3
Inhibit release of TSH and TRH
Thyroid production/function: What comes next?
Body requires thyroid hormone
Regulate growth and
development
TRH released from
hypothalamus
TRH released from hypothalamus
TSH stimulates the release of
T3 and T4
TSH secreted by anterior
pituitary gland
TSH stimulates the release of T3
and T4
TSH secreted by anterior
pituitary gland
Stimulates central nervous
system
Press ‘Enter’ to advance to next slide
when activity is completed.
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Thyroid agents for replacement can be synthetic or
natural and contain T3, T4, or both
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Medications:
◦ Levothroxine—contains T4
◦ Liothyronine—contains T3
Liotrix—contains T4 and T3
in a 4:1 ratio
◦ Thyroglobulin—contains T4
and T3 in a 2.5:1 ratio
◦ Thyroid USP contains T4 and
T3 variable ratio
Dose: 100 mcg
Dose: 25 mcg
Dose: 62.5-75 mcg
Dose: 65 mg
Dose: 65 mg
(Baer, Williams, 1992)
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Natural agents come from animal thyroid
◦ Thyroid USP
◦ Thyroglobulin
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Both contain T3 and T4
Synthetic agents are sodium salts of the Lisomers of the hormones
◦ Levothyroxine sodium
◦ Liothyronine sodium
◦ Liotrix
(Baer, Williams, 1992)
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Thyroid replacement hormones:
◦ Increase metabolic rate in the body’s tissues
◦ Stimulate protein synthesis
◦ Stimulate the heart to increase cardiac output
(Baer, Williams, 1992)
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What do thyroid replacement hormones do?
(Pick all that apply)
•Correct
•Protein synthesis is the process of cells’ building
proteins in the body—if the metabolism is slow,
Increase protein synthesis
so is the building process. Thyroid replacement
hormones help to increase the metabolism;
therefore, they increase protein synthesis
•Incorrect
Destroys
thyroid
tissues
•Anti-thyroid
medications
destroy
thyroid tissues.
Thyroid hormones will add to hormone levels
•Correct
•Thyroid replacement hormones will increase
Increase appetite
metabolism, which results in the need for more
fuel to run the body
•Incorrect
Inhibit
hormone
production
•Thyroid
replacement
hormones
only add to
hormone levels
What medication would a patient with
hypothyroidism receive?
•Incorrect
•This is an anti-thyroid drug. This medication
Propylithiouracil
inhibits the conversion of T4 to T3 and acts as an
immunosuppressant
•Correct
Levothyroxine
•This is a thyroid
replacement hormone and will
increase the metabolic rate in body tissues
•Incorrect
•This is a thyroid antagonist. It interferes with the
thyroid’s abilityPropranolol
to concentrate iodide ions and
therefore reduces the signs and symptoms of
hyperthyroidism
•Incorrect
•This is an anti-thyroid medication; it destroys
Radioactive iodine
thyroid tissues by inducing acute radiation
thyroiditis, which shrinks the thyroid gland
Adverse drug reactions:
 Most adverse drug reactions are from drug
toxicity
 Adverse effects will subside when drug is
temporarily removed
 What to look for:
GI signs/symptoms
-Diarrhea
-Abdominal cramps
-Weight loss
-Increased appetite
(Baer, Williams, 1992)
Cardiovascular
signs/symptoms
-Heart palpitations
-Tachycardia/aryhythmias
-Sweating
-Increased blood pressure
-Chest pain
Other signs/symptoms
-Headache
-Insomnia
-Tremors
-Nervousness
-Heat intolerance
-Fever
-Menstrual
irregularities
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Antithyroid agents (thyroid antagonists):
◦ Used for people with hyperthyroidism and Graves
disease
◦ Thyroid antagonists function by
 Interfering with hormone synthesis
 Modifying body tissues’ response to hormones
 Destroying the thyroid gland
(Baer, Williams, 1992)
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Antithyroid agent medications:
◦ Thionamides
 Propylthiouracil
 Methimazole
Biohazard
◦ Iodides
 Stable iodine
 Radioactive iodine
Microsoft Clipart
(Baer, Williams, 1992)
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How do these medications work?
◦ Thionamides
 Inhibit hormone production by reducing binding of
iodine and tyrosine
 Act as immunosuppressants
◦ Propylthiouracil
 Inhibits conversion of T4 to T3
◦ Stable iodine
 Quickly produces critical levels of iodide in the thyroid
gland, which temporarily decreases the rate of
hormone production
(Baer, Williams, 1992)
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Radioactive iodine
◦ Works two ways:
 Induces acute radiation thyroiditis which produces
chronic shrinking of the thyroid gland
 Destroys thyroid tissues
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Adverse drug reactions
◦ Most serious reaction to thionamide therapy:
 Fatal—granulocytopenia (appears 4-8 weeks after
treatment)
 Drop in white blood cell (WBC) count
(Baer, Williams, 1992)
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What to look for:
◦ Sore throat
◦ Fever
◦ Hypersensitivity—rash/puritis
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What to do:
◦ Obtain WBC count
◦ Obtain throat culture
(Baer, Williams, 1992)
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Iodides can cause chronic toxicity (dose
dependent)
What to look for:
◦ Brassy taste/burning
sensation in mouth
◦ Increased salivation
◦ Swelling of parotid
and submaxillary
glands
◦ Headache
(Baer, Williams, 1992)
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◦
◦
◦
◦
Rhinitis
Conjuctivitis
Gastric irritation
Bloody diarrhea
Anorexia
Depression
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What to look for (Potassium iodide):
◦
◦
◦
◦
◦
Tooth discoloration
Feeling of fullness in neck
Metallic taste in mouth
High risk for birth defects
Leukemia
(Baer, Williams, 1992)
http://www.indiamart.com/pioneerlabs/pcat-gifs/
products-small/potassiumiodide.jpg
Other Antithyroid Agents (Thyroid Antagonists):
 Not used as first line drug therapy
 Interfere with the thyroid’s ability to
concentrate iodide ions
 Reduce signs and symptoms of
hyperthyroidism
 Ionic inhibitors (adrenergic blocking agents)
◦ Propranolol
◦ Ipodate—used to decrease serum T3 levels
(Baer, Williams, 1992)
A patient diagnosed with hyperthyroidism calls and
complains of brassy taste and burning sensation in his
mouth. What category of medication is he taking?
Thyroid replacement
Incorrect
agent
Ace
Incorrect
inhibitor
Thyroid
Incorrect
antagonist
Antithyroid
Correctagent
Aging:
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Thyroid gland shrinks and shifts to lower neck
T3 and T4 levels decrease slightly
Thyroid function decreases (hypothyroidism)
Thyroid gland may enlarge or produce nodules
(goiter)
(Matfin, Porth, 2009)
Microsoft Clipart
Inflammation:
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Caused by Infection/Autoimmune response can result in
Thyroiditis (Hashimotos-hypothyroidism)
Hyperthyroidism (Graves disease)
Genetics:
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Polymorphisms (multiple forms of gene expression with
different phenotypes) are associated with variations in
serum hormone levels appear to contribute to
alterations in thyroid activity.
Defect in immune systems response leads to alteration
in thyroid function.
Microsoft Clipart
(Matfin, Porth, 2009)
Stress Response: (Biological or environmental)
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TSH increases
Corticosteroids are elevated during stress
Elevated corticosteroids inhibit immune response
Opportunity for infection occurs
Defect in immune response leads to decreased or
increased thyroid function ( the specific alteration
depends on which thyroid antibodies are produced
during altered immune response)
(Matfin, Porth, 2009)
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Mrs. Jones is a 44 year-old woman who came into the clinic
with complaints of just not feeling well. As you interview her,
she states that she is feeling tired lately and that she is cold
and needs to wear an extra sweater even on nice days. She
also complains that lately her monthly menstrual cycles have
been very heavy, and she’s been constipated even though she
has increased her daily fiber intake. Upon your initial exam,
you take her vital signs and find that her temperature is
96.4F; pulse is 54 bpm; blood pressure is 90/54. She is 5’2”
tall, and her weight today was 172 lb. You observe she has
gained 15 lb. from her last exam about a year ago. Upon your
objective observation, you notice that her skin is very dry and
her hair seems much thinner since her exam last year.

What diagnosis would you attribute to Mrs.
Jones’s signs and symptoms?
•Incorrect
Hyperthyroidism
Vitamin D
•Incorrect
deficiency
Hypothyroidism
Correct!!!
•Incorrect
Seasonal
allergies
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Now that you know Mrs. Jones has an
underactive thyroid gland (hypothyroidism),
how will you treat her?
•Correct
•Thyroid replacement hormones will
Givemetabolism
her levothyroxine
increase
and therefore create
energy through an increase in protein
synthesis
•Incorrect
•This a thyroid antagonist, it interferes with
Give her propranolol
the thyroid’s ability to concentrate iodide
ions and causes hypothyroidism
•Incorrect
•This is an anti-thyroid medication and will
Give
radioactive
iodine
destroyher
thyroid
tissues by shrinking
the
thyroid gland causing increased
hypothyroidism
•Incorrect
Send
her home
with of
•Although
constipation
is a symptom
hypothyroidism and Metamucil and exercise
Metamucil
and tell her to
can help, Mrs. Jones is suffering from
increase
hypothyroidism
and exercise
needs replacement
therapy

Hypothyroidism is an overactive thyroid.
•Incorrect
True causes
•Hyperthyroidism
increased metabolic processes
(overactive thyroid)
•Correct
•Hypothyroidism
False
causes decreased
metabolic processes

Now that Mrs. Jones is on levothyroxine
(thyroid replacement medication), how will
you manage her care? (pick all answers that apply)
•Correct
•Balanced nutrition will help Mrs.
Proper balance of nutrients
Jones maintain a healthy weight
•Minimize green leafy vegetables
•Correct
•Thyroid replacement medication
Thyroid
replacement
will
increase
Mrs. Jones’
metabolic
rate and will create
medication
increased energy and protein
synthesis
•Correct
•Mrs. Jones must have TSH levels
Follow up blood work to
monitored for medication dose
monitor
TSHher
levels
regulation
to keep
metabolic
rate at an optimum level
•Correct
•To
monitor
Mrs.to
Jones’
ongoing
Regular
visits
the doctor
health and wellness
You have successfully completed this tutorial
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OHSU Objectives Wiki, n.d. Anatomy of thyroid, slide 4. Retrieved from
http://www.ohsubooks.com/objectives/images/6/6c/Thyroid.jpg
Analgesia Database, n.d. Chemical Formula—T3 and T4, slide 7. Retrieved from
http://www.anaesthetist.com/icu/organs/endocr/thyroid/images/t3t4.gif
Poineer Laboratories, n.d. Chemical formula—potassium iodide, slide 46. Retrieved from
http://www.indiamart.com/pioneerlabs/pcat-gifs/products-small/potassiumiodide.jpg
Patient UK, n.d. Exophthalmos, slide 17. Retrieved from
http://www.patient.co.uk/images/OM934a.jpg
Clermont College Biology Home Page, n.d. Follicle of thyroid, slide 6. Retrieved from
http://biology.clc.uc.edu/fankhauser/Labs/Anatomy_&_Physiology/A&P202/Endocrine_System/his
tology_jpgs/thyroid_400x_P2252255lbd.JPG
Index of Sight Flash Images, n.d. Fred Flintstone, slide 26. Retrieved from
http://www.brsparty.com/site_flash/images/GrandPoobah160.jpg
Loyola University, n.d. Goiter, slide 17. Retrieved from
http://www.meddean.luc.edu/lumen/MedEd/Medicine/pulmonar/pdself/Goiter1.jpg
Hyperlink. Used with permission from Dr. Saul. Retrieved from
http://biologyinmotion.com/index.html
About.com, n.d. Hypothalamus, slide 25. Retrieved from
http://z.about.com/d/psychology/1/5/C/hypothalamus.jpg
Microsoft Clipart
mirage-samoyeds.com/health, n.d. Negative feedback, slide 31. Retrieved from
http://www.mirage-samoyeds.com/health/fig1a.gif
eHow, n.d. Thermostat, slide 26. Retrieved from
http://i.ehow.com/images/a04/hb/iv/troubleshoot-thermostat-800X800.jpg
ABC Australia, n.d. Thyroid gland, slide 5. Retrieved from
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