Thyroid (week 9) Flashcards
what does the thyroid secrete
thyroid hormone (T3, T4)
parathyroid hormone
calcitonin
what hormones secreted by the thyroid are involved in calcium balance
parathyroid hormone
calcitonin
what is calcium involved in in the body
nerve and muscle activity
precursors for thyroid hormone
monoiodotyrosine (MIT)
diiodotyrosine (DIT)
how is T4 formed
two DIT combine
how is T3 formed
one MIT and one DIT
how will thyroid hormone affect ability to exercise
too low or high levels of T3 and T4 can affect nerve and muscle function
effects of thyroid hormone
- necessary for development
- increases fat, protein, and glucose metabolism
- increases body temp
permissive hormone
a hormone that does not have a direct effect on tissue, but must be present for normal cell fxn
examples of permissive hormones
T3
T4
how does the body respond to sympathetic stimulation (norepinephrine) when T3&4 are in excess
excessive response
thyrotoxicosis
condition in which thyroid hormones are elevated inapproptiately
possible causes of thyrotoxicosis
- intrinsic influences, such as elevated TSH
2. extrinsic influences, such as ingesting thyroid hormone inappropriately
causes of goiter
- overstimulation of thyroid gland*
1. low iodine intake (overworks thyroid)
2. increased TSH
symptoms of thyrotoxicosis
- increased metabolism
- heat intolerance
- sensitivity to sympathetic stim
- goiter
Grave’s Disease
autoimmune disorder where antibodies overstimulate thyroid tissue, rather than destroy tissue
most common cause of hyperthyroidism and thyrotoxicosis
Grave’s Disease
LATS
Long Acting Thyroid Stimulator
- appear in the blood with Grave’s Disease
- thyroid stimulating antibodies
symptoms of Grave’s Disease
ongoing thyrotoxicosis unexplained weight loss night sweats fluctuating BP mood changes exopthalamos
exopthalamos
“bug eyes”
occurs due to excessive weight loss around eyes
thyrotoxic crisis AKA
thyroid storm
thyrotoxic crisis symptoms
hyperthermia
tachycardia
delirium
high output cardiac failure (heart can’t keep up with demands)
cause of thyrotoxic crisis
Graves Disease left untreated
treatment for thyrotoxic crisis
remove thyroid
radioactive iodine
propylthiouacil
what is radioactive iodine used for in stopping thyroid storm
destroy some thyroid tissue to decrease output of T3 T4
what does propylthiouracil do
blocks synthesis of thyroid hormone
how is propylthiouracil ideally administered
if thyroid storm caught in time, drug is titrated (T3 T4 monitored and dosage adjusted based on levels of T3 T4 in blood)
primary hypothyroidism
inflammation of the thyroid
causes of primary hypothyroidism
acute thyroiditis subacute thyroiditis autoimmune thyroiditis irradiation of thyroid iodine deficiency surgical removal of thyroid Lithium
acute thyroiditis cause
rare; usually due to bacterial infection of thyroid
subacute thyroiditis cause
nonbacterial infection of thyroid, often preceded by viral infection
autoimmune thyroiditis cause
autoimmune attack of thyroid tissue
acute thyroiditis can lead to autoimmune thyroiditis
subacute thyroiditis duration
2-4 months
treatment of subacute thyroiditis
corticosteroids
secondary hypothyroidism caused by
pituitary dysfunction/hypofunction
symptoms of hypothyroidism
- decreased energy, metabolism, heat production
- cold intolerance
- lethargy
- fatigue
- myxedemia
- hair texture change (more course)
myxedemia
AKA boggy edema; swelling where you can push your finger into it and leave an imprint that stays for a few minutes; usually occurs around eyes
Congenital Hypothyroidism (Cretinism)
absence of thyroid tissue at birth
incidence of cretinism
1 in 4000 live births
effects of cretinism if left untreated
mental retardation/developmental delay
stunted skeletal growth
treatment for Cretinism
hormone replacement therapy (synthroid)
highly effective if treatment initiated by 3-4 months of age; child can function completely normally with treatment
