Metabolic Disorders of the Thyroid and Adrenal Glands Flashcards
what is metabolic syndrome
a cluster of metabolic risk factors; excessive abdominal fat, high BP, high triglyceride and/or cholesterol levels, high blood sugar.
-can result in heart disease and type 2 diabetes
what are the diseases of the thyroid gladn
goiter, graves disease and hashimoto’s disease
what is goiter
abnormally large thyroid
what is graves disease
autoimmune disorder resulting in overproduction of thyroid hormones
what is hasmimotos disease
autoimmune disease (T-cell mediated) in which your immune system attacks the thyroid resulting in hypothyroidism
- The attack on thyroid follicular cells leads to apoptosis
- no thyroid follicular cells available to make T3 and T4
what are the diseases of the adrenal glands
addisons disease and cushings syndrome
what is addisons disease
underproduction of aldosterone and cortisol
what is cushings syndrome
cortisol overproduction
what does the thyroid gland produce
thyroid hormones and calcitonin
describe the anatomy of the thyroid gland and location
consists of 2 lobes and a central isthmus which gives it a bow tie like shape and sits anterior to the trachea
what element does the thyroid gland absorb
iodine
who is at higher risk for thyroid disorders
females
how much of the population have abnormal thyroid anatomy
15% of population
what is one of the most common findings of abnormal thyroid anatomy
thyroid nodules
what is the chemical name for T4
L-thyroxine
what is the chemical name for the metabolically active form of T3
3,5,3’ triiodothyronine
what is the chemical name for the metabolically inactive form of T3
3,3’,5’ triodothyronine
what is the major form of thyroid hormones in the blood
T4
which thyroid hormone has a longer half life
T4
how is T4 converted into T3 and where
in target cells by iodothyronine deiodinase
what do the 3 isoforms of iodothyronine deiodinase contain
a selenium metal ion
what can selenium deficiency lead to
decreased T3 levels
what does the synthesis of thyroid hormones involve
the protein thyroglobulin
describe how T4/T3 production is regulated by the thyroid
hypothalamus produces TRH which acts on the pituitary gland to produce TSH which acts on the thyroid gland to release T4 and T3 to target tissues. T3 and T4 act back on the pituitary gland and hypothalamus in a negative feedback loop
describe thyroid hormone biosynthesis
-iodine enters thyroid follicular cell by the iodine/Na symporter
-this initiates thyroglobulin secretion to be exported into the follicle colloid
- iodine is transported across the cell to the follicle colloid
- in the follicle colloid thyroglobulin undergoes iodination and conjugation
- it is endocytoses back into the thyroid follicular cell where it undergoes proteolysis to make thyroxine and triiodothyronine and T3 and T4 are released into the blood
what are some common symptoms of hyperthyroidism
- heart problems- arrhythmia or A-fib
- osteoporosis- too much thyroxine interferes with process of bone formation and calcium handling
-eye problems- graves opthalmopathy - red swollen skin- increased sensitivity to heat
- thyrotoxic crisis- sudden intensification of symptoms
- abnormal thermal regulation- night sweats
- brittle hair
what percentage of graves patients develop opthalmopathy
30%
what is the mechanism of action of graves disease
an antibody binds to the thyrotropin receptor which stimulates the thyroid to overproduce thyroid hormones
what are common symptoms of hypothyroidism
-fatigue
-sensitivity to cold
- constipation
-dry skin
- weight gain
- puffy face
-hoarseness
-muscle weakness, aches, tenderness and stiffness
-thinning hair
who is more likely to develop hashimotos disease
women are 8x more likely
what are the risk factors for hashimotos disease
addisons disease, celiac disease, pernicious anemia, sjogren’s syndrome, type 1 diabetes, vitiligo
what do patients develop as hashimotos syndrome progresses
goiter
what are some oral manifestations of hypothyroidism
-salivary gland enlargement
- compromised periodontal health
-delayed eruption
-enamel hypoplasia in both dentitions
- thick lips
-mouth breathing
what are some oral manifestations of hyperthyroidism
-increased susceptibility to caries
- increased susceptibility to periodontal disease
-enlargement of extraglandular thyroid tissue
what happens in thyroid follicular cell cancer
-point mutations on the TSH receptor or G-proteins associated with the receptor lead to hyperproliferation of thyroid cells
-growth factor receptors can be mutated that also affect thyroid cell proliferation
what are the dental complications of radioiodine therapy
-dry mouth
-increased risk of caries due to change in oral microbiome
what time of the day is hormone production the highest
during sleeping
what is perchlorate and what does it do
chemical originally developed for rocketfuel and explosives but is now in ground water and food supplies in US.
- blocks the thyroid glands ability to absorb and utilize dietary iodine
how do you do an iodine deficiency test on yourself
-use tincture of iodine and paint a patch on your arm
- inspect area in less than 8 hours. if color is done you have iodine deficiency
- in 24 hours if all color is gone you also likely need iodine
where are the adrenal glands located
on top of kidneys
what are the two parts of the adrenal galnds
the cortex and the medulla
what does the cortex of the adrenal glands produce
mineralocorticoids, glucocorticoids, and adrenal androgens
what does the medulla of the adrenal glands produce
catecholamines
what stimulates CRH release from the hypothalamus
low plasma cortisol levels, hypoglycemia, pyrogen, and stress
what suppresses CRH release from the hypothalamus
high plasma glucocorticoid levels
how are the adrenal glands regulated
CRH is released from the hypothalamus which acts on the anterior pituitary to release ACTH which acts on the adrenal gland to release their products
what is the main mineralocorticoid
aldosterone
what is the main glucocorticoid
cortisol
what are the main 2 adrenal androgens
DHEA and testosterone
what are the main catecholamines
adrenaline (epinephrine) and noradrenaline (norepinephrine)
what are the genomic actions of glucocorticoids
GC binds to receptor, receptor dimerizes and moves into the nucleus to upregulate through transactivation
- if receptor does not dimerize the receptor inhibits transcription (transrepression)
what is hyperaldosteronism
increased aldosterone which controls BP and body fat and K+ levels
what is pheochromocytoma
high levels of adrenaline
what are some of the adverse reactions to glucocorticoid use
- infections
-myopathia - osteoporosis
-pysch issues - weight gain
- skin thinning
- glaucoma
- cardio vascular
what are the symptoms of cushings syndrom
-fatty tissue deposition -> “moon face”
- osteoporosis -> pathological fractures of the mandible, maxilla, or alveolar bone
-delayed healing of fractures and also of tissue injuries
what are the symptoms of addisons disease
- bronzing, hyperpigmentation of the skin
- oral mucosal melanosis- buccal mucosa, tongue
- melanotic macules in the oral mucosa
what produces TSH and what is its functin
- produced by thyrotope cells in the anterior pituitary gland
- it regulates endocrine function of the thyroid gland
what produces TRH and what is its function
- produced by hypothalamus
- stimulates release of TSH and prolactin from the anterior pituitary
what is thyroid peroxidase
enzyme found in the thyroid that activates iodine for incpororation into tyrosine residues in thyroglobulin to produce T3 or T4
what is xerostomia
dry mouth
what is macroglossia
enlarged or swollen tongue
what is dysgeusia
distorted sense of taste
what is a treatment option for hyperthyroidism
radioiodine therapy
